Competitive Exams : GK & GS - Chemistry (Set 4)

Question 1

What is the oxidation state of Chromium ($ ext{Cr}$) in Potassium Dichromate ($ ext{K}_2 ext{Cr}_2 ext{O}_7$)?

Accepted Answer

C) +6

Answer

A) +3

Answer

B) +4

Answer

D) +7

Question 2

Calculate the molarity of a solution prepared by dissolving 10 gof$ ext{NaOH}$in enough water to make500 mLof solution. (Molar mass of$ ext{NaOH} = 40 ext{ g/mol}$)

Accepted Answer

B) 0.50 M

Answer

A) 0.25 M

Answer

C) 0.75 M

Answer

D) 1.00 M

Question 3

A given mass of gas occupies a volume of 400 mLat a pressure of750 mmHg. Assuming temperature remains constant, what will be its volume when the pressure is increased to 1000 mmHg?

Accepted Answer

B) 300 mL

Answer

A) 250 mL

Answer

C) 350 mL

Answer

D) 500 mL

Question 4

What is the pH of a 0.001 M aqueous solution of hydrochloric acid ($ ext{HCl}$), assuming complete dissociation?

Accepted Answer

C) 3

Answer

A) 1

Answer

B) 2

Answer

D) 4

Question 5

A radioactive element has a half-life of 15 days. What fraction of the original sample will remain undecayed after 45 days?

Accepted Answer

C) $\frac{1}{8}$

Answer

A) $\frac{1}{2}$

Answer

B) $\frac{1}{4}$

Answer

D) $\frac{1}{16}$

Question 6

Which of the following chemical formulas represents Plaster of Paris?

Accepted Answer

B) $	ext{CaSO}_4 \cdot \frac{1}{2}	ext{H}_2	ext{O}$

Answer

A) $	ext{CaSO}_4 \cdot 2	ext{H}_2	ext{O}$

Answer

C) $	ext{MgSO}_4 \cdot 7	ext{H}_2	ext{O}$

Answer

D) $	ext{Na}_2	ext{CO}_3 \cdot 10	ext{H}_2	ext{O}$

Question 7

Cinnabar is an important primary ore of which of the following metals?

Accepted Answer

C) Mercury

Answer

A) Copper

Answer

B) Lead

Answer

D) Zinc

Question 8

Which of the following elements possesses the highest electronegativity value on the Pauling scale?

Accepted Answer

C) Fluorine

Answer

A) Chlorine

Answer

B) Oxygen

Answer

D) Nitrogen

Question 9

Temporary hardness of water is primarily caused by the presence of dissolved hydrogen carbonates of which metals?

Accepted Answer

B) Calcium and Magnesium

Answer

A) Sodium and Potassium

Answer

C) Iron and Manganese

Answer

D) Aluminium and Copper

Question 10

How many moles of oxygen gas ($ ext{O}_2$) are required for the complete combustion of 2 moles of propane ($ ext{C}_3 ext{H}_8$)?

Accepted Answer

C) 10 moles

Answer

A) 5 moles

Answer

B) 8 moles

Answer

D) 12 moles

Question 11

Acid rain is primarily caused by atmospheric chemical reactions involving which pair of gases?

Accepted Answer

B) $	ext{SO}_2$and$	ext{NO}_2$

Answer

A) $	ext{CO}$and$	ext{CO}_2$

Answer

C) $	ext{CH}_4$and$	ext{CFCs}$

Answer

D) $	ext{O}_3$and$	ext{CO}_2$

Question 12

Vulcanization of natural rubber involves heating raw rubber with which substance to improve its cross-linking and durability?

Accepted Answer

C) Sulfur

Answer

A) Carbon black

Answer

B) Silicon

Answer

D) Phosphorus

Question 13

Which optical phenomenon describes the scattering of light by colloidal particles in a fine liquid or gas dispersion?

Accepted Answer

B) Tyndall Effect

Answer

A) Raman Effect

Answer

C) Doppler Effect

Answer

D) Zeeman Effect

Question 14

A reaction doubles its rate for every $10^\circ ext{C}$rise in temperature. If the rate is$R_0$at$20^\circ ext{C}$, what will be the rate at $50^\circ ext{C}$?

Accepted Answer

C) $8 R_0$

Answer

A) $3 R_0$

Answer

B) $6 R_0$

Answer

D) $16 R_0$

Question 15

Two atoms, ${}^{35}_{17} ext{Cl}$and${}^{37}_{17} ext{Cl}$, differ from each other in which of the following atomic parameters?

Accepted Answer

C) Number of neutrons

Answer

A) Number of protons

Answer

B) Number of electrons

Answer

D) Atomic number

Question 16

During the electrolysis of acidified water, which gas is liberated at the cathode?

Accepted Answer

B) Hydrogen

Answer

A) Oxygen

Answer

C) Nitrogen

Answer

D) Chlorine

Question 17

The organic functional group $- ext{CHO}$is characteristic of which family of organic compounds?

Accepted Answer

C) Aldehydes

Answer

A) Alcohols

Answer

B) Ketones

Answer

D) Carboxylic acids

Question 18

For a spontaneous chemical process occurring at constant temperature and pressure, which condition regarding Gibbs Free Energy Change ($\Delta G$) must hold true?

Accepted Answer

C) $\Delta G < 0$

Answer

A) $\Delta G > 0$

Answer

B) $\Delta G = 0$

Answer

D) $\Delta G = \Delta H$

Question 19

What is the volume occupied by 0.5 molesof an ideal gas at STP (where molar volume$= 22.4 ext{ L/mol}$)?

Accepted Answer

B) 11.2 L

Answer

A) 5.6 L

Answer

C) 22.4 L

Answer

D) 44.8 L

Question 20

Phenolphthalein indicator turns which color when added to a basic aqueous solution (pH > 8.3)?

Accepted Answer

C) Pink

Answer

A) Red

Answer

B) Yellow

Answer

D) Colorless

Set 4Competitive Exams : GK & GS - Chemistry