Chemistry - gkquestionsguru.com

491. Which chemical substance is used for making rat poison?

1. Ethyl Alcohol
2. Methyl Isocyanate
3. Potassium Cyanide
4. Ethyl Isocyanide

Option “3” is correct.
Potassium Cyanide (KCN) or Zinc Phosphide is a highly toxic chemical used as a rodenticide a poison to kill the mouse.

492. Which gas is used in fire extinguisher?

1. Carbon dioxide
2. Hydrogen
3. Oxygen
4. Sulphur dioxide

Option “1” is correct.
Carbon dioxide gas is used in a fire extinguisher to control small fires, often in emergency situations.

493. Which one of the following pairs is not correctly matched?

1. Ascorbic acid – Lemon
2. Maltose – Malt
3. Acetic acid – Curd
4. Formic acid – Red Ant

Option “3” is correct.
Lactic acid is found in curd not Acetic acid. Formic acid occurs in the body of red ants and in the stings of bees.

494. Which one of the following polymers is used for making bullet-proof windows?

1. Polycarbonates
2. Polyurethanes
3. Polystyrene
4. Polyamides

Option “1” is correct.
Bullet-resistant glass is made or manufactured by using polycarbonate, thermoplastic and layers of laminated glass.

495. The gas used to inflate the tyres of an aircraft is-

1. Hydrogen
2. Nitrogen
3. Helium
4. Neon

Option “2” is correct.
Nitrogen gas is used in the tyres of an aeroplane. This is because the nitrogen gas does not support combustion and can assist in preventing wheel fire when the aircraft lands .

496. Which of these consists carbon?

1. Lignite
2. Tin
3. Silver
4. Iron

Option “1” is correct.
Coal minerals are divided mainly into four types on the basis of the percentage of Carbon amount-
Peat, Lignite, Bituminous and Anthracite.

497. Of how many carats is the pure gold?

1. 22
2. 24
3. 28
4. 20

Option “2” is correct.
It is an extension of the older carat (Karat in North American spelling) system of denoting the purity of gold by fractions of 24, such as ’18 carat’ for an alloy with 75% (18 parts per 24) pure gold by mass.

498. Octane number is a measure of the quality of-

1. Edible oils
2. Petrol
3. Kerosene oil
4. Perfumed oil

Option “2” is correct.
The Octane number of a fuel is the measure of its antiknock quality when it is used in a spark ignition, internal combustion engine as compared to the antiknock quality of ISO-octane. The higher octane number of a fuel means the better antiknocking capacity for that fuel.

499. Table salt (NaCI) is a product of-

1. Weak acid ad weak base
2. Strong acid and strong base
3. Weak acid and strong base
4. Strong acid and weak basic

Option “2” is correct.
The compounds formed after reaction between the strong base and strong acid are known as neutral salt. Sodium chloride (NaCI) is an example of neutral which is salt also known as Table Salt.

500. Which gas is mixed with Oxygen for respiration by divers in deep sea?

1. Helium
2. Nitrogen
3. Xenon
4. Ammonia

Option “1” is correct.
Heliox is a breathing gas composed of a mixture of Helium (He) and Oxygen This is frequently used for respiration by divers in the deep sea.