Isobars have different: MCQ with Answer and Explanation

Isobars have different:
A. Both B and C
B. Mass numbers
C. Numbers of neutrons
D. Atomic numbers
Answer: Option A
Solution (By JKSSB Mock Tests)
Isobars are atoms of different elements, so they have different atomic numbers (protons). Since mass number is same, number of neutrons also differs. Example: ⁴⁰Ar (Z=18, N=22) and ⁴⁰Ca (Z=20, N=20). Mass number = 40 same. So both atomic number and neutrons differ. Option D is correct as both B and C are true.

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Hydrochloric acid is also known as:
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B. Muriatic acid
C. Aqua regia
D. Oil of vitriol

Correct Answer: Option B


Explanation:
Hydrochloric acid (HCl) was historically called muriatic acid or spirits of salt, produced from salt (NaCl) and sulfuric acid. Oil of vitriol is H₂SO₄. Aqua regia is a mixture of 3 parts HCl and 1 part HNO₃. Carbolic acid is phenol. HCl is present in gastric juice and used in metal cleaning and chemical synthesis.

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Question #2
The process of heating an ore strongly in the presence of excess air is called:
A. Calcination
B. Smelting
C. Roasting
D. Leaching

Correct Answer: Option C


Explanation:
Roasting involves heating sulfide ores in excess air to convert them to oxides and remove sulfur as SO₂. Example: 2ZnS + 3O₂ → 2ZnO + 2SO₂. Calcination is heating in absence of air (for carbonates/hydroxides). Smelting is reduction. Leaching uses chemicals.

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Enzymes are biological catalysts that are:
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Correct Answer: Option B


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