| Question: 61 |
How
many moles of electron weigh one kilogram? |
| Options: |
(a)  |
(b)  |
(c)  |
(d)  |
| Correct
Option: (d) |
Solution:
Mass
of 1 mole of electrons
= 9.108 × 10-31 × 6.023 × 1023 kg
 number of moles in 1
kg 
 |
| |
| Question: 62 |
Which
of the following volume (V) - temperature (T)
plots represents the behaviour of one mole of an ideal gas at
one atmospheric pressure? |
| Options: |
(a)  |
(b) |
(c)  |
(d) |
| Correct
Option: (c) |
Solution:
At STP, volume
occupied by 1 mole of an ideal gas = 22.4 L At constant
pressure, V  T
V1= 22.4 L, T1 = 273
K, T2 = 373 K
=
30.6 L |
| |
| Question: 63 |
If the
nitrogen atom had electronic configuration 1s7,
it would have energy lower than that of the normal ground
state configuration 1s2 2s2
2p3, because the electrons would be closer
to the nucleus. Yet, 1s7 is not observed
because it violates the |
| Options: |
(a) Heisenberg
uncertainty principle |
(b) Hund's rule |
| (c) Pauli
exclusion principle |
(d) Bohr postulate
of stationary orbits |
| Correct
Option: (c) |
| Solution:
According to Pauli's exclusion principle, no two electrons
can have the same quantum numbers, i.e. will not have the same
electronic configuration. Thus, s orbital can have only
two electrons, one with a clockwise spin and other with an
anti-clockwise spin. |
| |
| Question: 64 |
Rutherford's
experiment, which established the nuclear model of the atom,
used a beam of |
| Options: |
(a)  -particles,
which impinged on a metal foil and got absorbed |
(b)  -rays,
which impinged on a metal foil and ejected electrons |
| (c) helium atoms,
which impinged on a metal foil and got scattered |
(d) helium nuclei,
which impinged on a metal foil and got scattered |
| Correct
Option: (d) |
Solution:
Rutherford's experiment, which established the nuclear
model of the atom, used a beam of  -particles
(helium nuclei), which impinged on a metal (gold) foil and got
scattered. |
| |
| Question: 65 |
When
the temperature is increased, surface tension of water |
| Options: |
(a) increases |
(b) decreases |
| (c) remains
constant |
(d) shows
irregular behaviour |
| Correct
Option: (b) |
| Solution:
As the temperature increases, inter-molecular forces of
attraction decrease. As a result, surface tension decreases. |
| |
|
61-65
66-70 71-75
76-80 81-85
86-90 |
