OAS Prelims-2020 Daily Practice Set-11/01/2021:Chemistry

1. The gas used for artificial fruit ripening of green fruit is:
a) Ethylene
b) Acetylene
c) Ethane
d) Methane

2. The three elements most needed in common fertilizers are :
a) Sulphur, Phosphorous and Sodium
b) Nitrogen, Potassium and Phosphorous
c) Phosphorous, Sodium and Nitrogen
d) Calcium, Phosphorous and Potassium

3. Which one of the following metals pollutes the air of a city having large number of automobiles?
a) Cadmium
b) Chromium
c) Lead
d) Copper

4. What is the chemical name for ‘baking soda’?
a) Sodium carbonate
b) Sodium bicarbonate
c) Sodium nitrite
d) Sodium nitrate

5. An atomic pile is used for:
a) producing X-rays
b) conducting nuclear fission
c) coducting thermonuclear fusion
d) accelerating atoms

6. Which of the following gases is present under pressure in soft drinks?
a) Oxygen
b) Nitrogen
c) Carbon dioxide
d) Nitrous oxide

7. The substance which does not expand on going from liquid state to solid state is:
a) Water
b) Cast-iron
c) Aluminium
d) Type metal

18. The radio-active element used in heart pacemakers is:
a) Uranium
b) Deuterium
c) Plutonium
d) Radium

9. The element which is commonly used in nuclear for producing electricity by nuclear fission is:
a) Radium
b) Plutonium
c) Uranium
d) Deuterium

20. Table salt gets moist during rainy season because:
a) sodium chloride is hygroscopic
b) sodium chloride is deliquescent
c) sodium chloride contains some quantity of sodium iodide
d) sodium chloride contains hygroscopic impurities like magnesium chloride

Answers and Explanations

1. (a) Ethylene can promote ripening in tomatoes, bananas, citrus, pineapples, dates, persimmons,
pears, apples, melons, mangos, avocados, papayas and jujubes – a clear indication that the action of
ethylene is general and widespread amongst a number of fruits. It is clear that ethylene is a ripening hormone – a chemical substance produced by fruits with the specific biological phenomenon of accelerating the normal process of fruit maturation and senescence.

2. (b) Fertilizer (or fertiliser) is any organic or inorganic material of natural or synthetic origin (other than liming materials) that is added to a soil to supply one or more plant nutrients essential to the growth of plants. The three elements most needed in common fertilisers are Nitrogen. Potassium and Phosphorous

3. (c) The history of car pollution has been one of air and water contamination followed by regulated
improvement. Cars and trucks cause a lot of air the pollution in the world today, and contribute a lot to the most common and dangerous air pollutants. About 2.3 million tons of lead in lead acid (PbA) batteries is on the road now. Over 1 million tons of lead is used in making new batteries each year. In the past, motor vehicles were the biggest source of lead. But since leaded gasoline has been phased out, lead emissions have decreased by about 98 percent. Today, metal processing is the biggest source of atmospheric lead. The highest air concentrations are found in the vicinity of ferrous and nonferrous smelters and battery manufacturers.

4. (b) Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula NaHCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate). Since it has long been known and is widely used, the salt has many related names such as baking soda, bread soda, cooking soda, and bicarbonate of soda.

5. (b) An atomic pile is a nuclear reactor that uses controlled nuclear fission to generate energy. The
most common reactor consists of a large assembly of graphite (an allotropic form of carbon) blocks having rods of uranium metal (fuel).

6. (c) Carbon dioxide is present under pressure in soft drinks. Carbon dioxide adds that special sparkle and bite to the beverage and also acts as a mild preservative. Carbon dioxide is an uniquely suitable gas for soft drinks because it is inert, non-toxic, and relatively inexpensive and easy to liquefy.

7. (d) In printing, type metal (sometimes called hot metal) refers to the metal alloys used in traditional type founding and hot metal typesetting. Lead is the main constituent of these alloys. Antimony and tin are added to make the character produced durable and tough while reducing the difference between the coefficients of expansion of the matrix and the alloy. Pure metal melts and solidifies in a simple manner at a specific temperature. This is not the case with alloys.

8. (a) The actinides (or actinoids) are the chemical elements with atomic numbers between 90 and 109 inclusively. They occur between Groups 3 and 4 in Period 7 of the periodic table. All elements in this family are radioactive. Five actinides namely: thorium, protoactinium, uranium, neptunium, and plutonium have been found in nature. Plutonium is used in the manufacture of nuclear weapons and as the power source in nuclear power plants. On a smaller scale, it is also used as a power source in smaller devices such as the heart pacemaker.

9. (c) Uranium is used to produce a chemical and nuclear reaction which makes a lot of heat. This heat is used to turn water into steam, which turns turbines…turbines generate electricity.

10. (d) Table salt is refined salt, which contains about 97 to 99 percent sodium chloride. It usually contains substances that make it free-flowing (anticaking agents) such as sodium aluminosilicate or magnesium carbonate. Because of Hygroscopic nature of salt it become wet in rainy season as the salt absorbs moisture from environment.

Related and Sponsored Posts