Description : According to Bohr’s theory, the fourth stationary orbit of electrons in the hydrogen atom is a) 4 (0.053 nm) b) 9 (0.053 nm) c) 16 (0.053 nm) d) 25(0.053 nm)
Last Answer : c) 16 (0.053 nm)
Description : Free electrons are: (a) Fixed (b) Loosely bounded (c) Strongly fixed (d) Tightly bound
Last Answer : (b) Loosely bounded
Description : Addition of trivalent impurity to a semiconductor creates many (A) holes. (B) free electrons. (C) valance electrons. (D) bound electrons.
Last Answer : (B) free electrons.
Description : C and Si both have same lattice structure, having 4 bonding electrons in each. However, C is insulator where as Si is intrinsic semiconductor. This is because (1) The four bonding electrons in the case of C ... the case of C lie in the second orbit, whereas in the case of Si they lie in the third
Last Answer : (4) The four bonding electrons in the case of C lie in the second orbit, whereas in the case of Si they lie in the third
Description : The band above the valance band is called: a) Conduction band b) Filled band c) Forbidden band d) occupied band
Last Answer : a) Conduction band
Description : For Hydrogen atom, the allowed stationary orbits are those whose orbital angular momentum is equal to an integral multiple of h i.e., mvr = a) nh/2π b) nh x 2π c) nh / 2λ d) nh / 2πλ
Last Answer : a) nh/2π
Description : How many valance electrons does a neutral atom of silicon have?
Last Answer : That neutral silicon atom has four electrons in its valence shell.
Description : The quantized Bohr orbit radius of electron in hydrogen atom is given by a) n2 r3 b) nr1 c) n2 r2 d) n2 r1
Last Answer : d) n2 r1
Description : The value of first quantized Bohr orbit radius of hydrogen atom is a) 0.0053 nm b) 5.3 nm c) 0.053 nm d) 0.053 cm
Last Answer : c) 0.053 nm
Description : The outermost orbit of an atom is called?
Last Answer : Valence shell.
Description : Prosthetic groups differ from co-enzymes in that (a) they require metal ions for their activity (b) they (prosthetic groups) are tightly bound to apoenzymes (c) their association with apoenzymes is transient (d) they can serve as co-factors in a number of enzyme-catalyzed reactions.
Last Answer : (b) they (prosthetic groups) are tightly bound to apoenzymes
Description : Consider the following statements. (A) Coenzyme or metal ion that is tightly bound to enzyme protein is called prosthetic group. (B) A complete catalytic active enzyme with its bound prosthetic group is called apoenzyme. Select the ... ) (A) is true but (B) is false. (d) Both (A) and (B) are false
Last Answer : (d) Both (A) and (B) are false.
Description : Which of the following herbicides will be tightly bound to the soil? a). Trifluralin KOC(mL/g)= 7000 b). Paraquat KOC(mL/g)= 10,00,000 c). Glyphosate KOC(mL/g)= 24,000 d). Alachlor KOC(mL/g)= 124
Last Answer : b). Paraquat KOC(mL/g)= 10,00,000
Description : Herbicides are more tightly bound to soils under which of the condition a). Field capacity b). Saturated c). Both a and b d). Dry
Last Answer : d). Dry
Description : Is the field rotating or stationary?
Last Answer : Rotating. To confirm check Dennis T Hall.
Description : ___________ is not affected by a magnetic field a) Change in magnetic flux b) a moving electron c) a stationary proton d) current flowing in a conductor
Last Answer : c) a stationary proton
Description : The total energy of electron in the Bohr orbit is given by the formula, E = a) - ke2 /2r b) - ke2 /2r2 c) - k 2 e/2r d) - ke2 /r
Last Answer : a) - ke2 /2r
Description : The amount of energy required to completely remove an electron from the first Bohr orbit is a) 13.6 MeV b) 13.6 eV c) 1.36 MeV d) 1.36 eV
Last Answer : b) 13.6 eV
Description : The energy required to completely remove an electron from the first Bohr orbit is called a) excited energy b) ionization energy c) accelerated energy d) orbital energy
Last Answer : b) ionization energy
Description : The speed of hydrogen electron in the nth orbit is given by vn = a) 2λke2 / nh b) 2πke2 / λh c) 2πke2 / nh d) 2πke2 / h
Last Answer : c) 2πke2
Description : This layer is the outermost layer of the atmosphere satellites orbit the atmosphere in this layer?
Last Answer : Thermosphere and the exosphere
Description : The number of electrons in the penultimate orbit of krypton atom are
Last Answer : The number of electrons in the penultimate orbit of krypton atom are A. 8 B. 2 C. 18 D. 32
Description : The orbit followed by a moving electrons around the nucleus of an atom?
Last Answer : Shell
Description : In Bohr's theory of the atom, what force was responsible for holding the electrons in their orbit?
Last Answer : ANSWER: COULOMB FORCE or THE FORCE OF ATTRACTION BETWEEN THE PROTON (NUCLEUS) AND THE ELECTRON
Description : The number of electrons in the outer most orbit of carbon atom is?
Last Answer : The number of electrons in the outer most orbit of carbon atom is 4.
Description : In which material, valence electrons are tightly bounded to their parent atoms ? (a) Conductor (b) Semiconductor (c) Insulator (d) Magnetic
Last Answer : insulator(b)
Description : In the phenomenon of Laser production, atom can reside in the meta stable state for a) ~ 10-3 s b) ~ 10-8 s c) ~ 10-4 s d) ~ 10-10 s
Last Answer : a) ~ 10-3 s
Description : In the phenomenon of Laser production, atom can reside in the excited state only for a) 10-6 s b) 10-7 s c) 10-8 s d) 10-9 s
Last Answer : c) 10-8 s
Description : The radius of hydrogen atom is about a) 5 x 10-11 m b) 5 x 10-11 cm c) 5 x 10-11 mm d) 5 x 10-11 dm
Last Answer : a) 5 x 10-11 m
Description : Electron can exist in the atom but outside the nucleus because a) speed of electron is equal to the speed of light b) speed of electron is more than speed of light c) speed of electron is less than speed of light d) None of these
Last Answer : c) speed of electron is less than speed of light
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 : The incident photon absorbed by an atom in the ground state E1, thereby leaving the atom in the excited state E2 , is a) spontaneous absorption b) stimulated absorption c) induced absorption d) both b & c
Last Answer : d) both b & c
Description : A smallest three dimensional part of a crystal lattice is called. a) A particle b) A molecules c) A unit cell d) An atom
Last Answer : c) A unit cell
Description : For the production of X-rays, the electrons which strike with the target are a) slow moving b) fast moving c) vibrational electrons d) free electrons
Last Answer : b) fast moving
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 minimum frequency required to eject electrons from a metallic surface is called a) Critical frequency b) Peak value of frequency c) Threshold frequency d)Photo frequency
Last Answer : c) Threshold frequency
Description : The reverse current through semiconductor diode is due to (a) Minority carrier (b) majority carrier (c) electrons (d) holes
Last Answer : (a) Minority carrier
Description : Forward current through a semi-conductor diode circuit is due to ________ (a) Minority carriers (b) majority carriers (c) holes (d) electrons
Last Answer : (b) majority carriers
Description : N-type region has majority charge carriers as (a) Holes (b) protons (c) neutrons (d) electrons
Last Answer : (d) electrons
Description : Minority carriers in N-type are a) Holes b) Electrons c) Neutrons d) Protons
Last Answer : a) Holes
Description : The majority carriers in N-type substance are a) Holes b) Protons c) Neutrons d) Electrons
Last Answer : d) Electrons
Description : The electrostatic force of repulsion between two electrons at 1 metre is: (a) 9 × 109 N (b) 1.44 × 10−9 N (c) 2.30 × 10−28 N (d) 1 N
Last Answer : (c) 2.30 × 10−28 N
Description : The number of electrons in one coulomb charge is equal to: (a) 6.2 × 1018 electrons (b) Zero electrons (c) 1.6 × 10−22 electrons (d) 6.2 × 1021 electrons
Last Answer : (a) 6.2 × 1018 electrons
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 : The energy required to remove the electron from the outermost shell from a free and isolated atom of the element is called
Last Answer : Ionisation energy.
Description : The distance between the centre of the nucleus and the outermost electron shell of an atom is called
Last Answer : atomic size
Description : Why are electrons in the outermost shell are important?
Last Answer : Because they determine how the element will combine with otherelements
Description : What are transition elements? (1) Elements whose two outermost shells are incomplete (2) Elements which possess properties of both, metals and non-metals (3) They have eight electrons in the outermost shell (4) Elements whose three outermost shells are incomplete
Last Answer : (1) Elements whose two outermost shells are incomplete
Description : Elements with eight electrons in their outermost shell are called
Last Answer : noble gases