When a metal is heated in a flame, the electrons absorb energy and jump to higher energy state. On coming back to the lower energy siate, they emit light, which we can observe in (1) Raman spectra (2) Absorption spectra (3) Emission spectra (4) Fluorescence

When a metal is heated in a flame, the electrons absorb energy and jump to higher energy state. On coming back to the lower energy siate, they emit light, which we can observe in (1) Raman spectra (2) Absorption spectra (3) Emission spectra (4) Fluorescence
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Emission spectra
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When a metal is heated in a flame, the electrons absorb energy and jump to higher energy state. On coming back to the lower energy state, they emit light, which we can observe in - (1) Raman spectra (2) Absorption spectra (3) Emission spectra (4) Fluorescence

Description : When a metal is heated in a flame, the electrons absorb energy and jump to higher energy state. On coming back to the lower energy state, they emit light, which we can observe in - (1) Raman spectra (2) Absorption spectra (3) Emission spectra (4) Fluorescence

Last Answer : (3) Emission spectra Explanation: When a metal atom is strongly heated, its electrons absorb the heat energy and jump to a higher energy level. When the electron returns to its original position it ... to the energy the electron has released at each stage °fits fall back to its original state.

Sodium vapour lamps glow with yellow colour. This is due to - (1) sublimation of sodium to emit yellow colour (2) the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum (3) the low ionisation energy of sodium (4) its ability to absorb all other colours except yellow

Description : Sodium vapour lamps glow with yellow colour. This is due to - (1) sublimation of sodium to emit yellow colour (2) the emission of excess energy absorbed by sodium atoms, in the yellow region of the ... (3) the low ionisation energy of sodium (4) its ability to absorb all other colours except yellow

Last Answer : (2) the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum Explanation: Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.

Sodium vapour lamps glow with yellow colour. This is due to (1) sublimation of sodium to emit yellow colour (2) the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum (3) the low ionisation energy of sodium (4) its ability to absorb all other colours except yellow

Description : Sodium vapour lamps glow with yellow colour. This is due to (1) sublimation of sodium to emit yellow colour (2) the emission of excess energy absorbed by sodium atoms, in the yellow region of the ... (3) the low ionisation energy of sodium (4) its ability to absorb all other colours except yellow

Last Answer : the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum

A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case, (A) The cooling rate will be the same for the two spheres and hence the two spheres will have equal temperatures at any instant (B) Both the spheres will emit equal amount of radiation per unit time in the beginning (C) Both will absorb equal amount of radiation from the surrounding in the beginning (D) Both (B) & (C)

Description : A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case, (A) The cooling rate will be the same for the two spheres and hence the ... equal amount of radiation from the surrounding in the beginning (D) Both (B) & (C)

Last Answer : (D) Both (B) & (C)

The process, whereby electrons gain sufficient energy to be released from the surface of a thin, heated metal plate, is known as _____________. A. photo electric emission B. secondary emission C. thermionic emission D. regressive emission

Description : The process, whereby electrons gain sufficient energy to be released from the surface of a thin, heated metal plate, is known as _____________. A. photo electric emission B. secondary emission C. thermionic emission D. regressive emission

Last Answer : Answer: C

Why do cations emit colors when heated in a Bunsen burner flame?

Description : Why do cations emit colors when heated in a Bunsen burner flame?

Last Answer : Atoms were excited by heating, electrons move to a higher energy level and as these electrons fall back to a lower energy level, the specific radiation for the element is emitted.

Which one of the following statements is WRONG? (A) A singlet or triplet state may result when one of the electrons from the HOMO is excited to higher energy levels (B) In an excited singlet state, the spin of the electron in the higher energy orbital is paired with the electron in the ground state orbital (C) Triplet excited state is more stable than the singlet excited state (D) When the electron from the singlet excited state returns to ground state, the molecule always shows fluorescence phenomenon

Description : Which one of the following statements is WRONG? (A) A singlet or triplet state may result when one of the electrons from the HOMO is excited to higher energy levels (B) In an ... the electron from the singlet excited state returns to ground state, the molecule always shows fluorescence phenomenon

Last Answer : (C) Triplet excited state is more stable than the singlet excited state

In organic molecules, fluorescence seldom results from absorption of UV radiation of wavelengths lower than (A) 350 nm (B) 200 nm (C) 300 nm (D) 250 nm

Description : In organic molecules, fluorescence seldom results from absorption of UV radiation of wavelengths lower than (A) 350 nm (B) 200 nm (C) 300 nm (D) 250 nm

Last Answer : (A) 350 nm

Hydrogen atom is excited from ground state to another state with principal quantum number equal to 4. Then the number of spectral lines in the emission spectra will be - (1) 2 (2) 6 (3) 5 (4) 3

Description : Hydrogen atom is excited from ground state to another state with principal quantum number equal to 4. Then the number of spectral lines in the emission spectra will be - (1) 2 (2) 6 (3) 5 (4) 3

Last Answer : (2) 6 Explanation: Number of spectral lines from a state n to ground state is = n (n-1)/2 =4(4-1)/2 =12/2 =6

How are atomic emission spectra used to identify elements?

Description : How are atomic emission spectra used to identify elements?

Last Answer : Atomic emission spectra are chracteristic for each element.

Why are no two emission spectra for different elements ever the same?

Description : Why are no two emission spectra for different elements ever the same?

Last Answer : Because emission spectrum are the result of the electronconfiguration of the element and no two elements have exactly thesame electron configuration.

The reverse effect of X-ray emission is (1) Raman effect (2) Compton effect (3) Zeeman effect (4) Photoelectric

Description : The reverse effect of X-ray emission is (1) Raman effect (2) Compton effect (3) Zeeman effect (4) Photoelectric

Last Answer : (4) Photoelectric Explanation: When fast moving electrons strike on high atomic weight substance, X - ray is produced. In contrast, Photoelectric effect takes place when radiation of sufficient frequency ... and electrons are emitted. Hence, X ray is the inverse phenomenon of photoelectric effect.

The reverse effect of X–ray emission is (1) Raman effect (2) Compton effect (3) Zeeman effect (4) Photoelectric

Description : The reverse effect of X–ray emission is (1) Raman effect (2) Compton effect (3) Zeeman effect (4) Photoelectric

Last Answer : Photoelectric

The principle of emission of electrons from a metal surface, under the influence of light is known as

Last Answer : The principle of emission of electrons from a metal surface, under the influence of light is known as Photo electric emission.

A black body does not __________ radiation. (A) Absorb or emit (B) Refract (C) Reflect (D) Both (B) & (C)

Description : A black body does not __________ radiation. (A) Absorb or emit (B) Refract (C) Reflect (D) Both (B) & (C)

Last Answer : (D) Both (B) & (C)

Which metal gives violet colour in oxidising flame when heated with borax ?

Description : Which metal gives violet colour in oxidising flame when heated with borax ?

Last Answer : Which metal gives violet colour in oxidising flame when heated with borax ? A. Fe B. Pb C. Co D. Mn

According to Bohr's theory, an electron in one Bohr stationary orbit can go to a higher stationary orbit (a) By emission of electromagnetic radiation (b) Without any absorption or emission of electromagnetic radiation (c) With absorption of any electromagnetic radiation (d) With absorption of electromagnetic radiation of a particular frequency

Description : According to Bohr's theory, an electron in one Bohr stationary orbit can go to a higher stationary orbit (a) By emission of electromagnetic radiation (b) Without any absorption ... absorption of any electromagnetic radiation (d) With absorption of electromagnetic radiation of a particular frequency

Last Answer : Ans:(d)

Light colours absorb less heat therefore these are not heated as much as the black colour.

Description : Light colours absorb less heat therefore these are not heated as much as the black colour.

Last Answer : Ans: Dark colours do not exactly absorb more heat, but they do convert a higher percentage of light into heat. In the sun with a dark coloured shirt it gets hot, where a lighter ... and converted into heat. White objects reflect all visible light, where black objects absorb all visible light.

It is analogous to power dissipation to copper cables, impurities in the fiber absorb the light and covert it to heat. ∙ A. power loss ∙ B. absorption loss ∙ C. resistive loss ∙ D. heat loss

Description : It is analogous to power dissipation to copper cables, impurities in the fiber absorb the light and covert it to heat. ∙ A. power loss ∙ B. absorption loss ∙ C. resistive loss ∙ D. heat loss

Last Answer : B. absorption loss

A black body can absorb radiations of (1) lower wavelengths only (2) intermediate wavelengths only (3) higher wavelengths only (4) all wavelengths

Description : A black body can absorb radiations of (1) lower wavelengths only (2) intermediate wavelengths only (3) higher wavelengths only (4) all wavelengths

Last Answer : (4) all wavelengths Explanation: A black body is a theoretical object that absorbs 100% of the radiation that hits it. Therefore it reflects no radiation and appears perfectly black. At a particular ... as it must be able to absorb every wavelength to be sure of absorbing all incoming radiation.

A black body can absorb radiations of ; (1) lower wavelengths only (2) intermediate wavelengths only (3) higher wavelengths only (4) all wavelengths

Description : A black body can absorb radiations of ; (1) lower wavelengths only (2) intermediate wavelengths only (3) higher wavelengths only (4) all wavelengths

Last Answer : all wavelengths

Pick out the wrong statement. (A) A pale color of petroleum product indicates lower viscosity (B) Color of petroleum products indicates the degree of refinement (C) Lighter petroleum distillates are lighter in color than the heavier residual oils (D) Fluorescence of oils helps to detect its adulteration

Description : Pick out the wrong statement. (A) A pale color of petroleum product indicates lower viscosity (B) Color of petroleum products indicates the degree of refinement (C) Lighter petroleum distillates are ... in color than the heavier residual oils (D) Fluorescence of oils helps to detect its adulteration

Last Answer : (A) A pale color of petroleum product indicates lower viscosity

The mercury and sodium street lamps light up because of – (1) Atomic emission (2) Atomic absorption (3) Electron emission (4) Electron absorption

Description : The mercury and sodium street lamps light up because of – (1) Atomic emission (2) Atomic absorption (3) Electron emission (4) Electron absorption

Last Answer : (1) Atomic emission Explanation: The light in sodium vapour lamp and mercury vapour lamp is, because of electron emission. In case of Sodium Lamps, filaments of the lamp sputter ... energy levels and the electrons thus excited relax by emitting the characteristic monochromatic bright yellow light.

Stars appear twinkling because of ______ of light. (1) Reflection (2) Scattering (3) Emission (4) Absorption

Description : Stars appear twinkling because of ______ of light. (1) Reflection (2) Scattering (3) Emission (4) Absorption

Last Answer : (2) Scattering Explanation: The stars' light must travel through the Earth's multi-layered atmosphere, and as it does so it is refracted (bent) multiple times and in random directions. The phenomenon of ... star wink as though it is in motion. It is this action that our eyes translate as twinkling.

Absorption of light of one wave length by a substance and the re-emission of light of greater wavelength is called?

Description : Absorption of light of one wave length by a substance and the re-emission of light of greater wavelength is called?

Last Answer : Fluorescence

The blueness of the sky is mainly due to -------? A. The scattering of sunlight by air molecules (Answer) B. The presence of water vapor C. Absorption of blue light by the air D. Emission of blue light by the atmosphere

Description : The blueness of the sky is mainly due to -------? A. The scattering of sunlight by air molecules (Answer) B. The presence of water vapor C. Absorption of blue light by the air D. Emission of blue light by the atmosphere

Last Answer : A. The scattering of sunlight by air molecules (Answer)

The mercury and sodium street lamps light up because of : (1) Atomic emission (2) Atomic absorption (3) Electron emission (4) Electron absorption

Description : The mercury and sodium street lamps light up because of : (1) Atomic emission (2) Atomic absorption (3) Electron emission (4) Electron absorption

Last Answer : Atomic emission

Stars appear twinkling because of ......... of light. (1) Reflection (2) Scattering (3) Emission (4) Absorption

Description : Stars appear twinkling because of ......... of light. (1) Reflection (2) Scattering (3) Emission (4) Absorption

Last Answer : Scattering

Give reasons for the following observations: (a) The element carbon forms a very large number of compounds. (b) Air holes of a gas burner have to be adjusted when the heated vessels get blackened by the flame. (c) Use of synthetic detergents causes pollution of water. -Chemistry

Description : Give reasons for the following observations: (a) The element carbon forms a very large number of compounds. (b) Air holes of a gas burner have to be adjusted when the heated vessels get blackened by the flame. (c) Use of synthetic detergents causes pollution of water. -Chemistry

Last Answer : Answer. (a) Carbon forms large number of compounds since carbon is small in size and can form stable covalent bonds (catenation) and it shows tetravalency. (b) Air holes of gas burner are ... not get blackened. (c) Some synthetic detergents are non-biodegradable, therefore, cause pollution of water.

Pick out the wrong statement. (A) Biological oxygen demand (B.O.D.) value of a sewerage sample is always lower than its chemical oxygen demand (C.O.D.) value (B) Environmental pollution by NOx emission is much higher by four stroke petrol engines as compared to the two stroke engines (C) Temperature in stratosphere rises with increasing altitude (D) The characteristic of a green house body is that it allows the long wavelength incoming solar radiation to come in but does not allow the short wavelength infra red radiation to escape out of the earth's atmosphere

Description : Pick out the wrong statement. (A) Biological oxygen demand (B.O.D.) value of a sewerage sample is always lower than its chemical oxygen demand (C.O.D.) value (B) Environmental pollution by ... in but does not allow the short wavelength infra red radiation to escape out of the earth's atmosphere

Last Answer : (D) The characteristic of a green house body is that it allows the long wavelength incoming solar radiation to come in but does not allow the short wavelength infra red radiation to escape out of the earth's atmosphere

The maximum adiabatic flame temperature in air as compared to that in pure oxygen is (A) Much lower (B) Much higher (C) Same (D) Either lower or higher, depends on the type of fuel

Description : The maximum adiabatic flame temperature in air as compared to that in pure oxygen is (A) Much lower (B) Much higher (C) Same (D) Either lower or higher, depends on the type of fuel

Last Answer : (A) Much lower

Blast furnace gas compared to coke oven gas has (A) Lower ignition temperature (B) Narrower limit of inflammability (C) Higher calorific value (D) Lower theoretical flame temperature

Description : Blast furnace gas compared to coke oven gas has (A) Lower ignition temperature (B) Narrower limit of inflammability (C) Higher calorific value (D) Lower theoretical flame temperature

Last Answer : (D) Lower theoretical flame temperature

Combustion of pulverised coal compared to the lumpy coal (A) Provides better control of furnace temperature (B) Facilitates combustion with lower excess air (C) Provides higher thermal efficiency & flame temperature (D) All (A), (B) & (C)

Description : Combustion of pulverised coal compared to the lumpy coal (A) Provides better control of furnace temperature (B) Facilitates combustion with lower excess air (C) Provides higher thermal efficiency & flame temperature (D) All (A), (B) & (C)

Last Answer : (D) All (A), (B) & (C)

The maximum adiabatic flame temperature in air is __________ the maximum flame temperature in pure oxygen. (A) Lower than (B) Higher than(C) Same as(D) Not related to

Description : The maximum adiabatic flame temperature in air is __________ the maximum flame temperature in pure oxygen. (A) Lower than (B) Higher than (C) Same as (D) Not related to

Last Answer : (A) Lower than

In a circuit breaker the basic problem is to (a) maintain the arc (b) extinguish the arc (c) transmit large power (d) emit the ionizing electrons

Description : In a circuit breaker the basic problem is to (a) maintain the arc (b) extinguish the arc (c) transmit large power (d) emit the ionizing electrons

Last Answer : (c) transmit large power

How can a sheet of copper be made to emit electrons thermionically?

Description : How can a sheet of copper be made to emit electrons thermionically?

Last Answer : By heating it.

The process of moving from one energy level to another is called ____________. ∙ A. Spontaneous emission ∙ B. Excited emission ∙ C. Absorption ∙ D. Spontaneous decay

Description : The process of moving from one energy level to another is called ____________. ∙ A. Spontaneous emission ∙ B. Excited emission ∙ C. Absorption ∙ D. Spontaneous decay

Last Answer : C. Absorption

The process of decaying from one energy level to another energy level is called __________. ∙ A. Spontaneous emission ∙ B. Excited emission ∙ C. Absorption ∙ D. Any of these

Description : The process of decaying from one energy level to another energy level is called __________. ∙ A. Spontaneous emission ∙ B. Excited emission ∙ C. Absorption ∙ D. Any of these

Last Answer : A. Spontaneous emission

The emission of number of photo electrons depends upon a) The colour of the body b) The frequency of incident light c) The intensity of light d) All of the above

Description : The emission of number of photo electrons depends upon a) The colour of the body b) The frequency of incident light c) The intensity of light d) All of the above

Last Answer : c) The intensity of light

The reason why materials appear colored is (a) The selective absorption of spectral colors (b) The interaction between the light and the electrons of the dye molecules (c) The composition of the white light from various spectral colors (d) All of these

Description : The reason why materials appear colored is (a) The selective absorption of spectral colors (b) The interaction between the light and the electrons of the dye molecules (c) The composition of the white light from various spectral colors (d) All of these

Last Answer : All of these

The lustre of the metals is because of (1) high density, due to closed packing of atoms (2) high polish (3) reflection of light due to the presence of free electrons (4) absorption of light due to the presence of cavities

Description : The lustre of the metals is because of (1) high density, due to closed packing of atoms (2) high polish (3) reflection of light due to the presence of free electrons (4) absorption of light due to the presence of cavities

Last Answer : reflection of light due to the presence of free electrons

What are all properties of the stars that can measured from their spectra and light curves?

Description : What are all properties of the stars that can measured from their spectra and light curves?

Last Answer : Need answer

Compared to Chlorine, Bromine has: w) smaller atomic size x) higher density y) lower boiling point z) greater number of outer electrons

Description : Compared to Chlorine, Bromine has: w) smaller atomic size x) higher density y) lower boiling point z) greater number of outer electrons

Last Answer : ANSWER: X -- HIGHER DENSITY

A substance emits energy which is detected as a line emission in the visible region using a spectroscope. The origin of this energy is (a) Vibrational energy of the molecules (b) Rotational energy of the molecules (c) Energy of orbital electrons (d) Energy of protons in the nucleus.

Description : A substance emits energy which is detected as a line emission in the visible region using a spectroscope. The origin of this energy is (a) Vibrational energy of the molecules (b) Rotational energy of the molecules (c) Energy of orbital electrons (d) Energy of protons in the nucleus.

Last Answer : Ans:(c)

Which of the following HPLC detectors is used as a bulk property or general purpose detector? A. Electrochemical detector B. Fluorescence detector C. UV-Visible detector D. Evaporative Light scattering detector

Description : Which of the following HPLC detectors is used as a bulk property or general purpose detector? A. Electrochemical detector B. Fluorescence detector C. UV-Visible detector D. Evaporative Light scattering detector

Last Answer : D. Evaporative Light scattering detector

Stars twinkle but planets do not twinkle because – (1) they emit light of a constant intensity (2) their distance from the earth does not change with time (3) they are very far away from the earth resulting in decrease in intensity of light (4) they are nearer to the earth and hence we receive a greater amount of light and therefore minor variations in intensity are not noticeable

Description : Stars twinkle but planets do not twinkle because - (1) they emit light of a constant intensity (2) their distance from the earth does not change with time (3) they are very far away ... and hence we receive a greater amount of light and therefore minor variations in intensity are not noticeable

Last Answer : (4) they are nearer to the earth and hence we receive a greater amount of light and therefore minor variations in intensity are not noticeable Explanation: Eris is the most massive and second-largest ... orbiting the Sun, and the largest known body in the Solar System not visited by a spacecraft.

Stars twinkle but planets do not twinkle because (1) they emit light of a constant intensity (2) their distance from the earth does not change with time (3) they are very far away from the earth resulting in decrease in intensity of light (4) they are nearer to the earth and hence we receive a greater amount of light and therefore minor variations in intensity are not noticeable

Description : Stars twinkle but planets do not twinkle because (1) they emit light of a constant intensity (2) their distance from the earth does not change with time (3) they are very far away from ... and hence we receive a greater amount of light and therefore minor variations in intensity are not noticeable 

Last Answer : they are nearer to the earth and hence we receive a greater amount of light and therefore minor variations in intensity are not noticeable

What kind of combustion is observed in alkanes? Why do air holes of a gas burner have to be adjusted when vessel being heated gets blackened by the flame? -Science

Description : What kind of combustion is observed in alkanes? Why do air holes of a gas burner have to be adjusted when vessel being heated gets blackened by the flame? -Science

Last Answer : Alkanes are saturated hydrocarbons and generally burn in air with a blue, non-sooty flame. If the bottoms of the cooking vessels in our homes are getting blackened, it shows that the air holes of the gas stove are getting blocked and the fuel is not burning completely.

What happens when a piece of bangle is heated in a candle flame?

Description : What happens when a piece of bangle is heated in a candle flame?

Last Answer : When a piece of bangle is heated in a candle flame, it first becomes soft and then melts as glass does not have a definite melting point.

Why is it the "absorb" ends in b but "absorption" has a p in it?

Description : Why is it the "absorb" ends in b but "absorption" has a p in it?

Last Answer : Because English is a stupid f’ing language.