Chemistry Test

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Chemistry Test - 1

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Weekly Quiz Competition

Question 1
1 / -0.25

How many moles of magnesium phosphate, Mg₃ (PO₄ )₂ will contain 0.25 mole of oxygen atoms?

A
3.125 ×10^-2

B
1.25 ×10^-2

C
2.5 ×10^-2

D
0.02

Solution

Mg₃ (P0₄ )₂ →3Mg
→2 P
→8 mole oxygen
8 mole of oxygen - 1 mole Mg₃ (P0)₂
0.25 - ? 0.25/8 = 3 x 10^-2
Question 2
1 / -0.25

When an electron is added to neutral gaseous atom to convert it into a negative ion, the enthalpy change accompanying the process is called:

A
Ionisation enthalpy

B
Electron gain enthalpy

C
Lattice enthalpy

D
Hydration enthalpy

Solution

Electron affinity is defined as the change in energy (in kJ/mole) of a neutral atom (in the gaseous phase) when an electron is added to the atom to form a negative ion.
Question 3
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For emission line of atomic hydrogen from ni to n_f = 8, the plot of wave number against is:

(The Rydberg constant, RH is in wave number unit).

A
Linear with slope = - R_H

B
Linear with intercept = - R_H

C
Non linear

D
Linear with slope = R_H

Solution

m = R_H

Linear with slope R_H
Question 4
1 / -0.25

Two pi and half sigma bonds are present in:

A
N₂⁺

B
N₂

C
O₂⁺

D
O₂

Solution
Question 5
1 / -0.25

Adsorption of a gas follows Freundlich adsorption isotherm. In the given plot, x is the mass of the gas adsorbed on mass m of the adsorbent at pressure p. x/m is proportional to

A
P^1/4

B
P²

C
P

D
P^1/2

Solution

Slope =

⇒ n = 2

So,
Question 6
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The total number of isotopes of hydrogen and number of radioactive isotopes among them, respectively, are:

A
2 and 0

B
3 and 2

C
3 and 1

D
2 and 1

Solution

Total number of isotopes of hydrogen is 3

⇒

and only ₁³ H or ₁³ T is an Radioactive element.
Question 7
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0.5 moles of gas A and x moles of gas B exert a pressure of 200 Pa in a container of volume 10 m³ at 1000 K. given R is the gas constant in JK^-1 mol^-1 m, x is :

A

B

C

D

Solution

nT = (0.5 + x)

PV = n × R × T

200 × 10 = (0.5 + x) × R × 1000

2 = (0.5 + x) R
Question 8
1 / -0.25

In general, the properties that decrease and increase down a group in the periodic table, respectively, are:

A
electronegativity and electron gain enthalpy.

B
electronegativity and atomic radius.

C
atomic radius and electronegativity.

D
electron gain enthalpy and electronegativity.

Solution

The value of effective nuclear charge decreases down the group.

Hence, the electronegativity decreases and atomic radius increases on moving down the group.
Question 9
1 / -0.25

Phenyl diazonium salts form azo dye with

(1) Aniline

(2) Phenol

(3) N, N–dimethylaniline

(4) Anisole (methoxybenzene)

Of these statements :

A
2, 3, and 4 are correct

B
1, 3, and 4 are correct

C
1, 2, and 4 are correct

D
1, 2, and 3 are correct

Solution

PhN⁺ ≡ N is a weak electrophile that undergoes diazocoupling only with rings activated by −OH,−NH₂ ,−NHR or−NR₂ . The ring is not sufficiently activated by -OCH₃ and hence, anisole does not form azodye.
Question 10
1 / -0.25

Low spin complex is formed by

A
sp³ d² hybridisation

B
sp³ d hybridisation

C
d² sp³ hybridisation

D
sp³ hybridisation

Solution

Low spin complex utilises (n−1) d-orbital for hybridisation and thus the low spin complex is formed with d² sp³ hybridisation. Inner d-orbital complex is formed.
Question 11
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Which of the following hybridization pattern best describes the carbon atom in NCO⁻ ?

A
sp²

B
sp³

C
sp

D
sp³ d

Solution

NCO. is isoelectronic with CO₂ , which has a linear geometry in which C−atom is sp-hybridized.
Question 12
1 / -0.25

What is the shape and magnetic nature of permanganate ions?

A
Pyramidal diamagnetic

B
Tetrahedral, diamagnetic

C
Tetrahedral, paramagnetic

D
Planar, paramagnetic

Solution

The permanganate ions are tetrahedral. The π-bonding takes place by the overlap of p-orbitals of oxygen with d-orbitals of manganese. It is also diamagnetic due to the absence of an unpaired electron. The structure of permanganate ion is given below
Question 13
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“The mass and energy both are conserved in an isolated system”, is the statement of

A
second law of thermodynamics

B
third law of thermodynamics

C
the modified first law of thermodynamics

D
the first law of thermodynamics

Solution

"The mass and energy both are conserved in an isolated system*, is the statement at modified first law of thermodynamics. According to this law, if a certain amount of one kind of energy is produced, an equal amount of some other kind of energy is consumed so that the total energy in the universe remains constant.
Question 14
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The number of π-bonds present in benzoic acid molecule are

A
5

B
4

C
3

D
6

Solution

The number of π-bonds present in benzoic acid molecule are 4 (four). The structure of benzoic acid is as follows
Question 15
1 / -0.25

The combining ratios of hydrogen and oxygen in water and hydrogen peroxide are 1: 8 and 1 : 16. Which law is illustrated in this example?

A
Law of definite proportions

B
Law of conservation of mass

C
Gay Lussac's Jaw of combining volumes of gases

D
Law of multiple proportions

Solution

The combining ratios of hydrogen and oxygen . In water and hydrogen peroxide are 1 : 8 and 1 : 16. It is an example of a law of multiple proportions. According to this law, if two elements combine together to form several compounds then the weight of one of those elements, which combines with a fixed weight of the other, are in the ratio of simple whole numbers.
Question 16
1 / -0.25

The precipitation power of an electrolyte increases with

A
rise in temperature

B
atomic radii

C
ionic radii

D
charge of an ion

Solution

The precipitation power of an electrolyte increases with the charge of an ion. It can be explained on the basis of Hardy-Schulze rule. Greater the valence of the flocculating ion added, the greater is its power to cause precipitation.
Question 17
1 / -0.25

The highest oxidation state in plutonium (At. no. = 94) is

A
+6

B
+4

C
+5

D
+7

Solution

The highest oxidation state in plutonium (Atomic numbers = 94) is +7. It can show a greater range of oxidation states which (in part) is attributed to the fact that 5l, 6d and 7s teveisare of comparable energies. Plutonium (Pu) can show an oxidation state of +3, +4, +5, +6 and +7 in its compound.