The molecular weight of a Hydrogen atom _____ is kg.

(A) 1.79 × 10⁻²⁷ kg
(B) 1.73 × 10⁻²⁷ kg
(C) 1.68 × 10⁻²⁷ kg
(D) None of these

The molecular weight of a hydrogen atom is the mass of one hydrogen atom. To find this, we can use the standard atomic mass of hydrogen, which is approximately 1.008 atomic mass units (amu).

1 amu is equal to \( 1.66 \times 10^{-27} \) kilograms.

So, the mass of a hydrogen atom in kilograms is calculated as:

\[
1.008 \times 1.66 \times 10^{-27} \, \text{kg} \approx 1.67 \times 10^{-27} \, \text{kg}
\]

Looking at the options:
(A) \( 1.79 \times 10^{-27} \) kg
(B) \( 1.73 \times 10^{-27} \) kg
(C) \( 1.68 \times 10^{-27} \) kg
(D) None of these

The correct value is closest to \( 1.67 \times 10^{-27} \) kg, but this is not an exact match for any of the options provided. Therefore, the correct answer is:

**(D) None of these.**