Question

An astronaut gets thirsty on the moon. So, he uses a special equipment to make water by combining hydrogen and oxygen. What can you say about this water made on the moon?

• A. It will be different.
• B. It will be the same.
• C. On moon the water will have lighter mass than on earth.
• D. On moon the water will have heavier mass than on earth

Answer 1

The correct option is B

It will be the same.

According to the law of constant proportions, in any chemical compound, the elements are always present in a definite proportion by mass. So the mass ratio of the elements making up water will be the same, irrespective of the place.

$2H_2$ + $O_2$ $\to 2H_{2}O$

Even on the moon, the mass ratio of hydrogen and oxygen in water will be 1:8. This becomes quite obvious when you know that the water molecule is $H_{2}O$. If the ratio were to be different, it would be a different molecule and so would not be water anymore.