ECAT Chemistry Online Test With Answers

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ECAT Chemistry Online Test

Sr. # Questions Answers Choice
1 In Bohr model of hydrogen atom the distance between adjacent orbits increases away from the nucleus, the energy difference between the orbits Increases Decreases Reaming same Orbits coincide
2 Energy of electron in the infinite Bohr orbit of H-atom is 0 KJ/mole 1 KJ/mole -1 KJ/mole -1313.32 KJ/mole
3 Energy of electron in first orbit of H atom is -45.32 KJ/mole -82.08 KJ/mole -52.53 KJ/mole -1313.31 KJ/mole
4 The radius of first orbit of H-atom is 4.75 A° 3.84 A° 8.4 A° 0.529 A°
5 The order of distance between the various Bohr orbits is r<sub>2</sub>- r<sub>1</sub>&gt; r<sub>3</sub>- r<sub>2</sub>&gt; r<sub>4</sub>- r<sub>3</sub>&gt; ...... r<sub>1</sub>&gt; r<sub>2</sub>&gt; r<sub>2</sub>- r<sub>3</sub>&gt; r<sub>4</sub>-r<sub>3</sub>&gt; ..... r<sub>2</sub>-r<sub>1</sub>= r<sub>3</sub>- r<sub>2</sub>= r<sub>4</sub>- r<sub>3</sub>&gt; ..... r<sub>2</sub>- r<sub>1</sub>&gt; r<sub>3</sub>- r<sub>2</sub>&lt; r<sub>4</sub>- r<sub>3</sub>&lt; ....
6 Rutherford's planetary like picture of the atomic modal was defective because It did not describe the quantity of positive charge It did not explain the repulsion of protons within the nucleus No empty space between nucleus and the electrons Moving electron should radiate energy
7 Smallest charge of electricity that has been measured so far is Charge on a-rays Charge on electron (1.602 x 10<sup>-19</sup>C) Charge on x-rays Charge on gamma rays
8 In Millikan method the oil droplet falls under the force of gravity but it moves upward due to Electric field Magnetic field Incident light X-rays
9 In Millikan method for determination of charge on electron the air in the chamber is ionized by Protons Electric field X-rays a - particles
10 Neutrons are attracted by nucleus Neutrons carry out nuclear reactions Neutrons carry no charge Neutrons are electromagnetic radiations
11 When the 6d orbital is completed the entering electron goes into 7f 7 s 7 p 7 d
12 Positive particle in discharged tube is produced by ionization of gas molecules, which is caused by Gas molecules collide with anode Gas molecules are at high temperature Gas molecules produce X-rays Cathode rays remove electrons from gas molecules
13 When cathode rays strike the anode metal X-rays are emitted and not the positive rays because Cathode rays are material particles Cathode rays knock out electrons from anode, which emit X-rays when outer electron take their place Cathode rays are absorbed by the nucleus Cathode rays become heated
14 e/m of cathode rays is same but for positive rays e/m changes by changing gas in the discharge tube because Cathode rays are small sized particles Cathode rays have same charge Nature of cathode rays same for all gasses, but masses of nuclei are different for different gases Temperature of cathode rays higher
15 No cathode rays are produced in the discharged tube when gas is under ordinary pressure even if voltage of 5000 to 10000 is applies. This reason is Voltage is low Discharge tube is not coloured Gas does not conduct current under ordinary pressure Temperature low
16 Cathode rays drive a small paddle wheel placed in their path. This observation shows that Cathode rays travel in straight lines Cathode rays are negatively charged Cathode rays produce x-rays Cathode rays are material particles having momentum
17 The value of charge on electron is 1.602 x 10<sup>-19</sup>coulombs 1.602 x 10<sup>-18</sup>coulombs 1.602 x 10<sup>-17</sup>coulombs 1.602 x 10<sup>-16 </sup>coulombs
18 s p d f
19 The rules which describe the distribution of electron in atomic energy levels are Auf-ban principle, Pauli's exclusion principle. Hunds rule. The pauli exclusion principle refers to the Orientation of orbital in space Fact that two electrons in the same orbital should have opposite spins Energy of the orbital Spin of the electron
20 The principle quantum number describes The distance form the nucleus The shape of the orbital The orientation of the orbital The spin of the electron
21 The wave length of electron as wave is 0.5 nm. What is the wave length in meter 5 x 10<sup>-9</sup> 5 x 10<sup>-12</sup> 5 x 10<sup>-6</sup> 5 x 10<sup>-10</sup>
22 Orbitals having same energy are called Hybrid orbitals Valence orbitals Degenerate orbitals D-orbitals
23 When 3p orbital is complete, the entering electron goes into 4s 3d 4p 4f
24 In the ground state of an atom, the electron is present In the nucleus In the second shell Nearest to the nucleus Farthest from the nucleus
25 Quantum number values for 2p orbitals are n = 2, l = 1 n = 1, l = 2 n = 1, l = 0 n = 2, l = 0
26 The charge of an electron is determined by J.J. Thomson Crooks Perrin R.A.Millikan
27 Pauli's principle is applicable to Degenerate orbits Two electrons in the same orbital One electron None
28 The wave number of the light emitted by a certain source is 2 x 106m-1. The wavelength of this light will be 500 nm 500 m 200 nm 5 x 10<sup>7</sup>m
29 The nature of the positive rays depend on The nature of the electrode The nature of the discharge tube The nature of the residual gas All of the above
30 E = hv is the Spectral equation Plank's equation de Broglie's equation None of these
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