Chemistry (Part-I) (UPSC)

Total Questions: 34

21. Hydrogen fuel cell vehicles produce one of the following as "exhaust" [2010]

(a) NH₂
(b) CH
(c) H₂O
(d) H₂O₂

Correct Answer: (c) H₂O

Solution:A hydrogen vehicle is an alternative fuel vehicle that uses hydrogen as its onboard fuel for motive power. The hydrogen vehicle use hydrogen fuel cell for generation of motive power. These fuel cell in which hydrogen serve as a fuel and oxygen as an oxidant emits exhaust of water.

22. The function of heavy water in a nuclear reactor is to : [2011-1]

(a) slow down the speed of neutrons
(b) increase the speed of neutrons
(c) cool down the reactor
(d) stop the nuclear reaction

Correct Answer: (a) slow down the speed of neutrons

Solution:Heavy Water (D,O) or deuterium oxide is made up of two atoms of deuterium and one atom of oxygen. Deuterium is a stable isotope of hydrogen with double the mass of hydrogen due to presence of an extra neutron in its nucleus. Heavy Water displays similar physical and chemical properties but differs in nuclear properties when compared to ordinary water which makes it an extremely efficient material for use as moderator and coolant in Pressurized Heavy Water Reactor (PHWRs). Moderator is required in a Nuclear reactor to slow down the neutrons produced during the fission reaction so that the chain reaction can be sustained.

Heat energy produced in the core of reactor due to fission reaction is required to be carried away by a coolant. Heavy Water is used as a primary coolant to transport heat generated by the fission reaction to secondary coolant, light water. The light water takes the heat energy from Heavy Water and generates steam at an appropriate pressure for running steam turbines. Steam turbines drive generators to generate Electricity.

23. Water can dissolve more substances than any other liquid because. [2021-1]

(a) It is dipolar in nature
(b) It is a good conductor of heat
(c) It has high value of specific heat
(d) It is an oxide of hydrogen

Correct Answer: (a) It is dipolar in nature

Solution:The polar nature of water makes it a very good solvent for ionic and partially ionic compounds; Water molecules have a polar arrangement of the oxygen and hydrogen atoms one side (hydrogen) has a positive electrical charge and the other side (oxygen) had a negative charge. This allows the water molecule to become attracted to many other different types of molecules. Therefore, Correct Answer is "A".

24. Which one of the following is a mixed fertilizer? [1995]

(a) Urea
(b) CAN
(c) Ammonium sulphate
(d) NPK

Correct Answer: (d) NPK

Solution:Fertilizers are those compounds which provide essential primary nutrients (nitrogen, phosphorus and potassium) required for healthy growth of plants and crops. Nitrogeneous fertilizer provide nitrogen, phosphatic fertilizer provide phosphorus whereas potassh fertilizer provide potassium to soil. NPK fertilizers are mixed fertilizers. NPK fertilizers contains nitrogen, phosphorus and potassium in different proportion depending upon the requirement of soil.

25. The chemical used as a 'fixer' in photography is: [1995]

(a) Sodium sulphate
(b) Sodium thiosulphate
(c) Ammonium persulphate
(d) Borax

Correct Answer: (b) Sodium thiosulphate

Solution:Sodium thiosulphate is used in photography as a fixer. It removes Ag from negative by dissolving unexposed silver bromide resulting into formation of complex.

AgBr + 2Na2S2O, Na, [Ag(S₂O₃)₂] + NaBr

26. Which one of the following elements is alloyed with iron to produce steel which can resist high temperatures and also have high hardness and abrasion resistance? [1996]

(a) Aluminium
(b) Chromium
(c) Nickel
(d) Tungsten

Correct Answer: (b) Chromium

Solution:Steel is an alloy of iron and carbon. On mixing with carbon its strength and toughness got increased.

In order to make it further more temperature and abrasion resistant chromium is generally mixed with iron, it also increases its hardness and load bearing capacity.

Stainless steel is a category of steel consists (74% Fe, 18% Cr and 8% Ni) is corrosion resistant.

27. Which one of the following is not an essential micronutrient for plants? [1996]

(a) Boron
(b) Zinc
(c) Sodium
(d) Copper

Correct Answer: (c) Sodium

Solution:There are 13 essential nutrients required by plants for its healthy and proper growth. Now these nutrients are divided into two categories:
Macronutrients (nitrogen, phosphorus, potassium, calcium, magnesium and sulphur).

Micronutrients (iron, copper, manganese, zinc, boron, molybdenum and chlorine).

Additional mineral nutrient elements which are beneficial but not necessary are sodium, cobalt, vanadium, nickel, solenium, aluminium and silicon.

Thus boron, zinc and copper falls into category of essential micronutrients while sodium does not.

28. The most reactive among the halogens is : [1997]

(a) Fluorine
(b) Chlorine
(c) Bromine
(d) lodine

Correct Answer: (a) Fluorine

Solution:Not just in the halogen family, but in the whole periodic table it is the most reactive non-metal. It belongs to second period and group 17 of the periodic table. Fluorine is the most reactive halogen because of several factors, including its small size, high electro-negativity, and ability to form strong bonds with other elements. The size of the Fluorine atom is smallest in its period and group. Since it has just two shells, the nuclear hold is quite strong, thus the tendency to gain an electron is very high.

29. Match List I with List II and select the correct answer using the codes given below the lists: [1998]

List-I	List-II
A. Blue vitriol	1. Sodium bicarbonate
B. Epsom salt	2. Sodium hydroxide
C. Baking soda	3. Magnesium sulphate
D. Caustic soda	4. Copper sulphate

Codes:

	A	B	C	D
(a)	3	4	2	1
(b)	4	3	2	1
(c)	3	4	1	2
(d)	4	3	1	2

(a)
(b)
(c)
(d) 4

Correct Answer: (d) 4

Solution:Blue vitriol is blue, crystalline hydrous solution of copper sulphate, CuSO 5H,O, one of the most important industrial copper salts, used in insecticides, germicides, and hair dyes and in the processing of leather and textiles.

Magnesium sulphate is a chemical compound containing magnesium, sulphur and oxygen, with the formula MgSO It is often encountered as the heptahydrate epsomite (MgSO, 7H,O), commonly called "Epsom salt".

Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula NaHCO,. The salt has many related names such as baking soda, bread soda, cooking soda, bicarbonate of soda.
Caustic soda or sodium hydroxide is an essential ingredient in an array of industrial applications. In addition, consumers use caustic soda when using cleaners, such as oven and drain cleaners.

30. Match List-I with List-II and select the correct answer using the codes given below the lists: [1998]

List-I	List-II
A. Potassium bromide	1. Fertiliser
B. Potassium nitrate	2. Photography
C. Potassium sulphate	3. Bakery
D. Monopotassium tartarate	4. Gun powder

Codes:

	A	B	C	D
(a)	2	4	1	3
(b)	2	3	1	4
(c)	4	2	3	1
(d)	4	2	1	3

Correct Answer: (a)

Solution:Potassium bromide is used in photography as a restrainer in black and white developer formulas. Gun powder, also called black powder, is a mixture of sulphur, charcoal, and potassium nitrate.

Gun powder can be made by just using potassium nitrate and charcoal (or alternatively without charcoal), but without the sulphur (or coal), the powder is not as strong. Potassium sulfate is primarily used as a fertilizer. Mono potassium tartrate is used in bakery by combination with baking soda it results in to evolution of CO, which is used for baking cakes.

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Chemistry (Part-I) (UPSC)

21. Hydrogen fuel cell vehicles produce one of the following as "exhaust" [2010]

22. The function of heavy water in a nuclear reactor is to : [2011-1]

23. Water can dissolve more substances than any other liquid because. [2021-1]

24. Which one of the following is a mixed fertilizer? [1995]

25. The chemical used as a 'fixer' in photography is: [1995]

26. Which one of the following elements is alloyed with iron to produce steel which can resist high temperatures and also have high hardness and abrasion resistance? [1996]

27. Which one of the following is not an essential micronutrient for plants? [1996]

28. The most reactive among the halogens is : [1997]

29. Match List I with List II and select the correct answer using the codes given below the lists: [1998]

30. Match List-I with List-II and select the correct answer using the codes given below the lists: [1998]

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