An atom has mass number 39 and 20 neutrons. Its atomic number is: MCQ with Answer and Explanation

An atom has mass number 39 and 20 neutrons. Its atomic number is:
A. 20
B. 39
C. 19
D. 59
Answer: Option C
Solution (By JKSSB Mock Tests)
Atomic number (Z) = Mass number (A) – Number of neutrons (N) = 39 – 20 = 19. This is potassium (K). Number of protons equals atomic number. In a neutral atom, electrons also equal Z.

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The Solvay process is used for the manufacture of:
A. Ammonia
B. Sulfuric acid
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Correct Answer: Option D


Explanation:
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Sulphuric acid is known as:
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B. Muriatic acid
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Correct Answer: Option D


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Ethanol is chemically:
A. CH₃OH
B. CH₃COOH
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Correct Answer: Option D


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Ethanol, commonly known as ethyl alcohol, has the chemical formula C₂H₅OH. Methanol is CH₃OH. Acetic acid (ethanoic acid) is CH₃COOH, and propionic acid is C₂H₅COOH. Ethanol is widely used as a solvent, in alcoholic beverages, and as a biofuel.

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