ECAT Pre Engineering Chemistry Chapter 5 MCQ Test With Answer

The number of de-electrons retained in Fe²⁺ (At.No. of Fe = 26) ions is

• 3 A
• 4 B
• 5 C
• 6 D

With the reference of w/m ratio of anode rays, the e/m ratio of cathode rays s:

• Greater. A
• same. B
• Smaller. C
• Not fixed. D

1 erg of energy corresponds to

• 6.02 x 10²³J/mol A
• 6.02 x 10¹⁶J/mol B
• 1 erg/mol C
• 10^-7J/mol D

The wave number of light emitted by a certain source is 2 x 10⁵m. The wavelength of this light will be:

• 500 NM. A
• 500 M. B
• 200 NM. C
• 5 x 10⁷m D

When cathode rays strike the anode metal X-rays are emitted and not the positive rays because

• Cathode rays are material particles A
• Cathode rays knock out electrons from anode, which emit X-rays when outer electron take their place B
• Cathode rays are absorbed by the nucleus C
• Cathode rays become heated D

The four quantum numbers of the valency electron of potassium are

• 4,1,1,1/2 A
• 4,0,0,1/2 B
• 4,1,0,1/2 C
• 4,4,0,1/2 D

The number of neutrons in the element ⁹₄Be is

• 4 A
• 5 B
• 9 C
• 13 D

The degenerate orbitals p-sub shell are

• 2 A
• 3 B
• 5 C
• 7 D

In the ground state, an element has 13 electrons in its M shell. The element is

• Copper A
• Chromium B
• Nickel C
• Iron D

The radius of first orbit of hydrogen atom

• 0.329 A° A
• 0.429 A° B
• 0.529 A° C
• 0.229 A° D

Which of the following element's outermost orbits last electron has magnetic quantum number m=0?

• Na A
• O B
• Cl C
• N D

Which one of the following statements is true about discovery of neutrons?

• These particles were formed by the bombardment of Alpha-particles on Beryllium. A
• These particles are formed by the spiting of alpha-particles. B
• These particles were discovered by natural radioactivity. C
• None of above. D

The size of electronic shell is described by

• Azimuthal Q. no A
• Magnetic Q.No B
• Spin Q. No C
• Principle Q. No D

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 A
• Cathode rays have same charge B
• Nature of cathode rays same for all gasses, but masses of nuclei are different for different gases C
• Temperature of cathode rays higher D

The total number of orbitals possible for the quantum number n is

• n A
• n² B
• 2n C
• 2n² D

Which of the following was discovered first:

• Charge to mass ratio of electrons. A
• Mass of electrons. B
• Charge of electrons. C
• All of above at same time. D

Maximum potential energy that an electron can have within the atom is:

• Equal to zero. A
• Less than zero. B
• Greater than zero. C
• Infinite D

Bohr model of atom is contradicted by:

• Planck's quantum theory A
• Pauli's exclusion theory B
• Heisenberg's uncertainty principle. C
• All of above. D

Splitting of spectral lines when atoms are subjected to strong electric field is called:

• Zeeman effect. A
• Stark effect B
• Photoelectric effect. C
• Compton effect. D

Which is not true with respect to cathode rays?

• A stream of electrons A
• Charged particles B
• Move with speed as that of light C
• Can be deflected by magnetic fields D

• s A
• p B
• d C
• f D

Which of the following is not charged particle

• Proton A
• Electron B
• Neutron C
• Hydrogen nucleus D

Find the magnetic moment of a divalent ion in aqueous solution if its atomic number is 25

• 3.0 BM A
• 4.9 BM B
• 5.9 BM C
• 6.9 BM D

In the atomic emission spectrum the lines which appear bright, appear dark in absorption spectrum because

• The radiations emitted in emission spectrum are absorbed in absorption spectrum A
• Atomic emission spectrum is continuous B
• Atomic absorption spectrum is continuous C
• Distance between the lines increases D

n + l value for 4f will

• 2 A
• 5 B
• 7 C
• 9 D

The ratio of the ionization energy of H and Be³⁺is

• 1 : 1 A
• 1 : 3 B
• 1 : 9 C
• 1 : 16 D

The correct set of quantum numbers (n,l and m) respectively of the unpaired electron of chlorine atom is

• 2,1,0 A
• 2,1,1 B
• 3,1,1 C
• 3,2,1 D

When the electron jumps form second third, fourth orbit to the fist orbit, the transitions are known as

• Balmer series A
• Lyman series B
• Pfund series C
• Brackett series D

The spectrum of He is expected to be similar to that of

• H A
• Na B
• He⁺ C
• Li⁺ D

When potassium metal is exposed to violet light

• Ejection of electrons takes place A
• Ejection of some potassium atoms occurs B
• There is no effect C
• The absorption of electrons takes place D