General Science Jkssb Chemistry Set 1 Mcqs (504 MCQs) | JKSSB & SSC Quiz

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jkssb chemistry set 1 mcqs

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Practice Questions

504 Total
Question 101 Discuss
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The black coating formed on silver jewellery is:

A
AgNO3
B
Ag2CO3
C
AgCl
D
Ag2 S

Answer & Explanation

Correct Option: D

Silver tarnishes over time when it naturally reacts with trace amounts of hydrogen sulfide gas (H2S) present in the ambient air. This historically common chemical reaction slowly forms a thin, protective black layer of silver sulfide (Ag2S) directly on the surface of the jewelry.
Question 102 Discuss
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Which of the following raw materials is NOT used to prepare the baking soda?

A
NH3
B
Na2CO3
C
NaCl
D
H2O

Answer & Explanation

Correct Option: B

In the historical Solvay process, the raw materials used to synthesize baking soda (sodium bicarbonate) are sodium chloride, water, carbon dioxide, and ammonia. Sodium carbonate (Na2CO3) is a subsequent product formed later by thermally decomposing the baking soda, not a starting raw material.
Question 103 Discuss
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The iodine value of oil and fat indicates:

A
Degree of unsaturation
B
Saponification value
C
Acid value
D
Peroxide value

Answer & Explanation

Correct Option: A

The iodine value is a standard chemical analytical test that historically and currently measures the exact degree of unsaturation in fats and oils. A higher iodine value indicates a higher quantity of reactive carbon-carbon double bonds present within the fatty acid chains.
Question 104 Discuss
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Moseley observed that the plot of √𝑣 against atomic number (𝑍) gave a straigth line. What does 𝑣 indicate here?

A
Frequency of 𝛾-rays emitted
B
Frequency of 𝛼-rays emitted
C
Frequency of X-rays emitted
D
Frequency of 𝛽-rays emitted

Answer & Explanation

Correct Option: C

In 1913, Henry Moseley discovered a systematic relationship between the frequencies of X-rays emitted by elements and their atomic numbers, establishing Moseley's Law. This historically proved that the atomic number is a genuine physical property linked to nuclear charge, leading to the definitive reorganization of the periodic table.
Question 105 Discuss
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0.25 g of an organic compound, on treatment with fuming nitric acid followed by AgNO3, gave 0.22 g of AgBr . The percentage of bromine in the compound is ...........

A
88.00%
B
50.00%
C
37.45%
D
34.04%

Answer & Explanation

Correct Option: C

This demonstrates the Carius halogen method, developed by Georg Ludwig Carius in 1860 for quantitative chemical analysis. By calculating the mass fraction of bromine in the precipitated 0.22g of silver bromide, the mass percentage of bromine in the original compound calculates perfectly to 37.45%.
Question 106 Discuss
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To which of the following classes of compounds does cyclohexane belong?

A
Heterocyclic compound
B
Non-benzenoid aromatic compound
C
Benzenoid aromatic compound
D
Alicyclic compound

Answer & Explanation

Correct Option: D

Cyclohexane is classified structurally as an alicyclic compound because it features a closed, non-aromatic carbon ring. It lacks the delocalized pi-electron system required to be classified as aromatic, existing solely as a fully saturated cyclic hydrocarbon.
Question 107 Discuss
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Non-polar molecules possess .

A
partial charge
B
no dipole moment
C
permanent dipole moment
D
instantaneous dipole moment

Answer & Explanation

Correct Option: D

While non-polar molecules inherently lack a permanent dipole, the continuous, random movement of their electrons can temporarily create uneven charge distributions. These fleeting electrical imbalances generate instantaneous dipole moments, which are the driving force behind London dispersion interactions.
Question 108 Discuss
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The approximate number of water molecules present in 9 gm of water is .

A
6.022 ×1023
B
6.022 × 1022
C
3.011 ×1023
D
9.023 ×1023

Answer & Explanation

Correct Option: C

The molar mass of water is 18 g/mol, meaning a 9-gram sample represents exactly half a mole. According to Avogadro's historical constant, half a mole physically contains roughly 3.011 × 10^23 discrete molecules.
Question 109 Discuss
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0.25 g of an organic compound gave 0.20 gof CO2 after complete combustion. The percentage composition of carbon is .

A
80.00%
B
78.18%
C
21.82%
D
4.60%

Answer & Explanation

Correct Option: C

Using Liebig's method for elemental analysis, the carbon in the sample is entirely converted to CO2. Since carbon makes up 12/44 of the mass of CO2, the absolute carbon content in the original 0.25 g sample mathematically calculates to 21.82%.
Question 110 Discuss
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Which of the following pollutants is responsible for the acidification of ocean?

A
Carbon monoxide (CO)
B
Carbon dioxide (CO2)
C
Nitrogen Dioxide (NO2)
D
Sulphur dioxide (SO2)

Answer & Explanation

Correct Option: B

The Earth's oceans naturally absorb approximately a quarter of the carbon dioxide released into the atmosphere by human activities. When this CO2 dissolves in seawater, it forms carbonic acid, which progressively lowers the water's pH and triggers widespread ocean acidification.
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