NON-MEATALS, B. Hydrogen and its Compounds

Total Questions: 28

1. An element X has four electrons in its outermost orbit. What will be the formula of its compounds with Hydrogen? [43rd B.P.S.C. (Pre) 1999]

(a) X₄H
(b) X₄H₄ 
(c) XH₃
(d) XH₄

Correct Answer: (d)
Solution:

The compound of element X, which has four electrons in its outermost orbit, will be XH₄. This is because element X needs four more electrons to complete its octet, and each hydrogen atom provides one electron to form a covalent bond.

2. According to weight, the percentage of Hydrogen in water (H₂O), is — [Uttrakhand U.D.A./L.D.A. (Mains) 2006]

Correct Answer: (d) 11.11%
Solution:Percentage of composition is the percent by mass of each element present in a compound.

In water H₂O,  = 2+16 =18 g/mol

Number of Hydrogen atoms present in water = 2.

Mass of Hydrogen atoms = 1×2= 2g

Percentage of Hydrogen in water = (2/18)×100=11.11%

3. One mole of hydrogen gas burns in excess of oxygen to give 290 kJ of heat. What is the amount of heat produced when 4g of Hydrogen gas is burnt under the same conditions? [I.A.S. (Pre) 1994]

Correct Answer: (c) 580 kJ
Solution:Explanation:

1 Mole of H₂(Hydrogen) = 2 gm

Energy released by 4 gm = 290×2= kJ

4. Burning of hydrogen produces — [47th B.P.S.C. (Pre) 2005]

Correct Answer: (d) Water
Solution:Hydrogen gas is highly flammable and burns in air over a wide concentration range of 4% to 75%. When it burns with oxygen, it produces water.

2H₂(g)+O₂(g)2H₂O(l)

5. Which one of the following fuels causes minimum air pollution? [U.P. Lower Sub. (Pre) 2015]

Correct Answer: (b) Hydrogen
Solution:Hydrogen is the purest combustion fuel. Burning hydrogen generates water. Fossil fuels like coal, kerosene, and diesel release carbon dioxide and harmful gases when burned.

6. Heavy water is a type of — [U.P.P.C.S. (Pre) 1993]

Correct Answer: (e) Coolant & Moderator
Solution:Heavy water (D₂O) deuterium oxide is used as a moderator as well as a in nuclear reactors because it slows down neutrons effectively and also has a low probability of absorption of neutrons. Deuterium is an isotope of hydrogen which comprises both a neutron and a proton. Deuterium or heavy hydrogen reacts with oxygen to form deuterium oxide (D₂O) also known as heavy water. Normal water (H₂O) also used as a moderator as well as a coolant in ( light water reactors)/ nuclear reactors.

7. The chemical formula for heavy water is — [66th B.P.S.C. (Pre) (Re. Exam) 2020]

Correct Answer: (c) D₂O
Solution:Deuterium is an isotope of hydrogen which comprises both a neutron and a proton. Deuterium or heavy hydrogen reacts with oxygen to form deuterium oxide (D₂O) also known as heavy water.

8. The chemical formula of Heavy Water is — [Jharkhand P.C.S. (Pre) 2003]

Correct Answer: (b) D₂O
Solution:Deuterium is an isotope of hydrogen which comprises both a neutron and a proton. Deuterium or heavy hydrogen reacts with oxygen to form deuterium oxide (D₂O) also known as heavy water.

9. The substance used as moderator and coolant both, in nuclear reactors is — [U.P. P.C.S. (Pre) 2016]

Correct Answer: (b) Heavy water
Solution:Heavy water (D₂O) deuterium oxide is used as a moderator as well as a in nuclear reactors because it slows down neutrons effectively and also has a low probability of absorption of neutrons. Deuterium is an isotope of hydrogen which comprises both a neutron and a proton. Deuterium or heavy hydrogen reacts with oxygen to form deuterium oxide (D₂O) also known as heavy water. Ordinary water () can also act as a moderator and coolant (in light water reactors). So, according to question asks for a substance used as both, and heavy water fits this description perfectly and efficiently.

10. What is heavy water? [M.P.P.C.S. (Pre) 1991]

Correct Answer: (a) Oxygen + Heavy Hydrogen
Solution:Deuterium is an isotope of hydrogen which comprises both a neutron and a proton. Deuterium or heavy hydrogen reacts with oxygen to form deuterium oxide (D₂O) also known as heavy water.