Find the molecular mass of methane (CH4). Class 9

Find the molecular mass of methane (CH₄). Class 9

Question 1.

Find the molecular mass of methane (CH₄). Class 9

Atomic mass - C = 12 u; H = 1 u.

Answer:

CH₄ contains: 1 carbon atom, 4 hydrogen atoms.

Molecular mass of CH₄

= (12 u × 1) + (1 u × 4)

= 12 + 4 = 16 u

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Question 2.

Find the formula unit mass of potassium chloride (KCl). Class 9

Atomic mass — K = 39 u; Cl = 35.5 u.

Answer:

KCl contains: 1 potassium ion and 1 chloride ion.

Formula unit mass of KCl

= (39 u × 1) + (35.5 u × 1)

= 39 + 35.5 = 74.5 u