Chemistry (Part-XIII)

1. Silica gel is a— [S.S.C. Online Graduate Level (T-I) 30.08.2016 (Shift-II) ]

(a) moisturizer
(b) flavouring agent
(c) drying agent
(d) delicious food

Correct Answer: (c) drying agent

Solution:Silica gel is a kind of drying agent. It is silicon dioxide (SiO₂), which is in the form of sand with fine pores. Moisture is absorbed by its tiny pore-forming particles.

2. Which of the following functional group of carbon does not contain oxygen? [S.S.C. Online MTS (T-I) 20.08.2019 (Shift-I) ]

(a) Alcohol
(b) Halogen
(c) Aldehyde
(d) Ketones

Correct Answer: (b) Halogen

Solution:The functional group of carbon such as alcohol (ROH), aldehyde (RCHO), ketone (RCOR), etc. contains oxygen, while the halogen group (CR-F, R-Cl, R-Br, and R-I) lacks oxygen.

3. How many Carbon and Hydrogen atoms are there in Propane, respectively? [S.S.C. Online Graduate Level (T-I) 7.03.2020 (Shift-III) ]

(a) 3,8
(b) 4,7
(c) 2,6
(d) 2,4

Correct Answer: (a) 3,8

Solution:Propane is a hydrocarbon with the chemical formula C₃H₈. In this, 3 atoms of carbon and 8 atoms of hydrogen are linked to each other by a single bond.

4. Alkenes were earlier known as ______ . [S.S.C. Online CHSL (T-I) 24.01.2017 (Shift-III) ]

(a) Paraffins
(b) Titoffins
(c) Olefins
(d) Meloffins

Correct Answer: (c) Olefins

Solution:Alkenes were formerly known as olefins. In organic chemistry, an alkene or olefin is an unsaturated chemical compound containing at least one carbon-to-carbon double bond and no other functional group, forming a homogeneous hydrocarbon chain. Together they form a homogeneous hydrocarbon chain with the simple formula CₙH₂ₙ.

5. Which of the following gases reduces the Oxygen carrying capacity of the blood? [S.S.C. Online Graduate Level (T-I) 7.06.2019 (Shift-I) ]

(a) Nitrous Oxide
(b) Carbon Monoxide
(c) Carbon Dioxide
(d) Nitric Oxide

Correct Answer: (b) Carbon Monoxide

Solution:Carbon monoxide reduces the oxygen-carrying capacity of the blood, as this gas combines with hemoglobin (Hb) present in the blood to form carboxyhemoglobin (COHb). It is a permanent compound, due to which the transport of oxygen by hemoglobin in the blood is inhibited.

6. Which is known as carbolic acid? [S.S.C. Online Graduate Level (T-I) 10.09.2016 (Shift-I) ]

(a) Phenol
(b) Ethanol
(c) Acetic acid
(d) Oxalic acid

Correct Answer: (a) Phenol

Solution:Phenol is an aromatic organic compound with the molecular formula C₆H₅OH. It consists of a hydroxyl group (-OH) directly bonded to a benzene ring. Historically, it was obtained from coal tar and was known as carbolic acid due to its acidic properties and its origin from coal. It's used in disinfectants, antiseptics, and in the synthesis of various compounds.

7. What is the formula of butane gas? [S.S.C. Online CHSL (T-I) 19.03.2020 (Shift-I) ]

(a) C₅H₁₀
(b) C₄H₆
(c) C₄H₁₀
(d) C₄H₈

Correct Answer: (c) C₄H₁₀

Solution:Butane is an alkane.

"But-" indicates four carbon atoms (n=4).
Using the alkane general formula CnH2n+2: C₄H(2×4)+2 = C₄H₈+2 = C₄H₁₀.

8. Ethane gas has a slightly taste. [S.S.C. Online CHSL (T-I) 18.01.2017 (Shift-I) ]

(a) sweet
(b) bitter
(c) sour
(d) salty

Correct Answer: (a) sweet

Solution:Ethane (

) is a colorless, odorless, and slightly sweet-tasting gas. While it's generally not consumed for its taste, its taste is noted in specific laboratory or industrial contexts when describing its properties.

9. Liquefied Petroleum Gas (LPG) used for cooking in homes is a combination of: [S.S.C. Online MTS (T-I) 18.10.2021 (Shift-I) ]

(a) methane and propane
(b) propane and butane
(c) hexane and propane
(d) methane and butane

Correct Answer: (b) propane and butane

Solution:LPG is a flammable mixture of hydrocarbon gases used as fuel in heating appliances and vehicles. The primary components of LPG are propane ( $C₃ H₈$ ) and butane (C₄H₁₀), or a mixture of the two. The exact ratio can vary depending on the supplier and the climate (propane is preferred in colder climates due to its lower boiling point).

10. LPG is a mixture of ______. [S.S.C. Online CHSL (T-I) 20.01.2017 (Shift-III) ]

(a) Methane and Butane
(b) Butane and Propane
(c) Methane and Propane
(d) Ethane and Propane

Correct Answer: (b) Butane and Propane