Description : Transistors are made from (a) Plastic (b) metals (c)insulators (d) doped semiconductors
Last Answer : d) doped semiconductors
Description : Which one of the following phenomena can be studied with -rays a) Photoelectric effect b) Compton effect c) Pair production d) All of the above
Last Answer : a) Photoelectric effect
Description : Photoelectric effect was discovered by a) Einstein b) G.P.Thomson c) Hallwachs d) Lenard
Last Answer : a) Einstein
Description : Laser is the acronym for a) Light Amplification by Stimulated Emission of Radiation b) Light Amplification by Spontaneous Emission of Radiation c) Light Amplified by Stimulated Emission of Radiation d) Light Amplification by Standard Emission of Radiation
Last Answer : a) Light Amplification by Stimulated Emission of Radiation
Description : Substances of conductivity between 10–10 10–20 (n m )–1 are: a) Insulators b) Semiconductors c)Super conductors d)Good conductors
Last Answer : a) Insulators
Description : he substances of conductivity of the order of 10–6 – 10–4 (m)–1 are : a) Insulators b) Super conductors c) Semiconductors d)Good conductors
Last Answer : d)Good conductors
Description : The emission in which the atom emits a photon of energy hf = E2 – E1 , in any arbitrary direction is a) Spontaneous emission b) stimulated emission c) induced emission d) both a & c
Last Answer : d) both a & c
Description : Which one of the following scientists regarded light as electromagnetic waves? a) Newton b) Galileo c) de Broglie d) Maxwell
Last Answer : d) Maxwell
Description : Which one of the following waves requires a material medium for their propagation? a) Light waves b) X– rays c) -rays d) Sound waves
Last Answer : d) Sound waves
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.
Description : The source of the sun's energy is the process of – (1) Photoelectric emission (2) Nuclear fission (3) Nuclear fusion (4) Thermionic emission
Last Answer : (3) Nuclear fusion Explanation: The Sun formed about 4.6 billion years ago from the gravitational collapse of a region within a large molecular cloud. Most of the matter gathered in the center, ... thermonuclear fusion in its core. It is thought that almost all other stars form by this process.
Description : The source of the Sun's energy is the process of – (1) Photoelectric emission (2) Nuclear fission (3) Nuclear fusion (4) Thermionic emission
Last Answer : (3) Nuclear fusion Explanation: Nuclear fusion is a nuclear reaction in which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. During this process, matter ... fusing nuclei is converted to energy which is released. Fusion is the process that powers active stars.
Description : The method used to produce electron emission in most vacuum tubes is known as ____________. A. photoelectric emission B. secondary electric emission C. cold cathodic electric emission D. thermionic emission
Last Answer : Answer: D
Description : The reverse effect of X–ray emission is (1) Raman effect (2) Compton effect (3) Zeeman effect (4) Photoelectric
Last Answer : Photoelectric
Description : The source of the Sun’s energy is the process of (1) Photoelectric emission (2) Nuclear fission (3) Nuclear fusion (4) Thermionic emission
Last Answer : Nuclear fusion
Description : Metals are good conductors of electricity because they have: (a) Large number of bounded electrons (b) Small number of electrons (c) Large number of free electrons (d) Small number of free electrons
Last Answer : (c) Large number of free electrons
Description : Which of the following statement is correct: (a) Similar charges attract each other (b) Similar charges attract and repel each other (c) Similar charges repel each other (d) Similar charges neither attract nor repel 9. Metals are good conductors of electricity because they have:
Last Answer : (c) Similar charges repel each other
Description : .Diffractionof electromagneticwaves a. is caused by reflections from the ground b. arises only with spherical wavefronts c. will occur when the waves pass through a large slot d.may occuraroundthe edge of asharpobstacle
Last Answer : d.may occuraroundthe edge of asharpobstacle
Description : The absorption ofradiowaves bythe atmosphere depends on a. their frequency b. their distance from the transmitter c. the polarization of the waves d. the polarization of the atmosphere
Last Answer : a. their frequency
Description : .In electromagneticwaves,polarization a. is caused by reflection b.isdue to the transversenature ofthewaves c. results from the longitudinal nature of the waves d. is always vertical in an isotropic medium
Last Answer : b.isdue to the transversenature ofthewaves
Description : FrequenciesintheUHFrange normallypropagate bymeans of a. ground waves b. sky waves c. surface waves d.spacewaves
Last Answer : d.spacewaves
Description : By the transition of inner shell electrons in heavy atoms, high energy photons are emitted which are a) gamma rays b) X-rays c) radio waves d) photon rays
Last Answer : b) X-rays
Description : The concept that particles can behave like waves was given by a) Compton b) De-Broglie c) G.P. Thomson d) Germer
Last Answer : b) De-Broglie
Description : de Broglie’s relation for matter waves was experimentally verified by: a) Davisson b) Germer c) G.P. Thomson d) All the these
Last Answer : c) G.P. Thomson
Description : The concept of matter waves was introduced by a) Davisson and Germer b) de Broglie c) Einstein d) Schrodinger
Last Answer : b) de Broglie
Description : Which one of the following radiations has the most energetic photon? a) T.V. waves b) Micro waves c) X-rays d) - rays
Last Answer : d) - rays
Description : In a half wave rectifier the rms value of AC component of the waves (a) Zero (b) Equal to DC value (c) More than DC value (d) Less than DC value
Last Answer : b) Equal to DC value
Description : Superconductors are those elements – (1) Whose conductivity is intermediate between metals and insulators (2) Whose resistance falls almost to zero at very low temperature (3) Which conduct electricity only at super-high temperature (4) Which conduct electricity only, at super-high temperatures
Last Answer : (2) Whose resistance falls almost to zero at very low temperature Explanation: Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in ... lines from the interior of the superconductor as it transitions into the superconducting state.
Description : The metals occuring at the lower most position in the electromotive series (A) Do not resist corrosion (B) Resist corrosion very strongly (C) Are very brittle (D) Are heat insulators
Last Answer : (B) Resist corrosion very strongly
Description : Figure out the odd statement about ceramics in the following (a) Good insulators of heat and electricity (b) Usually less desire than metals (c) Ductile in nature (d) Contains both metallic and nonmetallic elements
Last Answer : (c) Ductile in nature
Description : Superconductors are those elements (1) Whose conductivity is intermediate between metals and insulators (2) Whose resistance falls almost to zero at very low temperatures (3) which turn into insulators at very low temperatures (4) which conduct electricity only at super-high temperatures
Last Answer : Whose resistance falls almost to zero at very low temperatures
Description : They wrote a paper describing how it was possible to use stimulated emission for amplifying light waves (laser) as well as microwaves (maser). ∙ A. Theodore Maiman ∙ B. KC Kao and GA Bockham ∙ C. Charles Townes and Arthur Schawlow ∙ D. Kapron, Keck and Maurer
Last Answer : C. Charles Townes and Arthur Schawlow
Description : They wrote a paper describing how it was possible to use stimulated emission for amplifying light waves (laser) as well as microwaves (maser).
Last Answer : Charles Townes and Arthur Schawlow
Description : What is the oxidation number of alkali metals ?
Last Answer : Oxidation number of alkali metals + 1.
Description : What are the alkali metals ?
Last Answer : The remaining 6 elements of hydrogen in group 1 of the periodic table .
Description : For alkali metals, which one of the following trends is incorrect ?
Last Answer : For alkali metals, which one of the following trends is incorrect ? A. Hydration energy `: Li^(+) gt Na^(+) ... D. Atomic size `: Li lt Na lt K lt Rb`
Description : Select similarly between alkali metals and coinage metals.
Last Answer : Select similarly between alkali metals and coinage metals. A. Both are required to store in organic ... same number of electron(s) in outermost shell
Description : Standard reduction potential of alkali metals have high negative values.
Last Answer : Explain : Standard reduction potential of alkali metals have high negative values.
Description : Hydrogen shows similarity with alkali metals as well as halogens.
Last Answer : Explain : Hydrogen shows similarity with alkali metals as well as halogens.
Description : Give reasons : a. Alkali metals have low ionization energies. b. Inert gases have exceptionally high ionization energies.
Last Answer : Give reasons : a. Alkali metals have low ionization energies. b. Inert gases have ... d. Noble gases possess relatively large atomic size.
Description : What is the most active group of nonmetals noble gases alkaline earth halogens alkali metals?
Last Answer : The most active metals are alkali metals.The most active nonmetals are halogens.
Description : Who has the most active group of nonmetals noble gases alkaline earth halogens alkali metals?
Last Answer : Kevin
Description : In an outline the subtopics are alkali metals and halogens what would the main topic of the outline be?
Last Answer : hi
Description : Why second ionization energy of alkali metals are higher than first ionization energy?
Last Answer : The attraction between the electrons involved and the atomic nucleus is stronger.
Description : Alkali metals can
Last Answer : easily lose electrons
Description : The alkali metals have (a) Low ionization energy (b) High electronegativities (c) High m.p. (d) Electron configuration of ns2np1
Last Answer : Ans:(a)
Description : f-block elements are also called (a) Alkali metals (b) Inner transition elements (c) Transition elements (d) Transuranic elements
Last Answer : Ans:(b)
Description : Which one occupies the lowermost position in the electromotive series of metals? (A) Aluminium (B) Noble metals (Ag, Pt, Au) (C) Zinc (D) Alkali metals (K, Na, Li)
Last Answer : (B) Noble metals (Ag, Pt, Au)
Description : How does the of Hydration Enthalpy of alkaline earth metals vary & compare it with alkali metals
Last Answer : Ans The hydration enthalpies of alkaline earth metal ions decrease with increase in ionic size down the group. Be2+> Mg2+ > Ca2+ > Sr2+ > Ba2+ The hydration enthalpies of alkaline earth metal ions ... MgCl2 and CaCl2 exist as MgCl2.6H2O and CaCl2· 6H2O while NaCl and KCl do not form such hydrates.
Description : How does the of Ionization Enthalpy of alkaline earth metals vary in comparison to alkali metals
Last Answer : Ans The alkaline earth metals have low ionization enthalpies due to fairly large size of the atoms. Since the atomic size increases down the group, their ionization enthalpy decreases The first ... enthalpies of the alkaline earth metals are smaller than those of the corresponding alkali metals.