The air pressure inside a submarine is 0.62 atm. What would be the height of a
column of mercury balanced by this pressure?

471.2 mmHg

Explanation:

Given that :

The air pressure inside a submarine is 0.62 atm

What would be the height of a  column of mercury balanced by this pressure?

The standard air pressure in a mercury containing vessel keeps the mercury raised up to 760 mm higher, this is relatively synonymous to the force from the weight of that column in the vessel.

Now in 0.62 atm  air pressure inside a submarine, the height of the column of mercury balanced by this pressure will be:

0.62 × 760 mmHg = 471.2 mmHg

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

answer: -

reaction:

na + cl ⇌ nacl

balanced chemical equation:

na + 2cl ⇌ nacl2

sodium + clorine goes to form sodium chloride (table salt).

the product is nacl2.

and the reactants are na and cl.

(note: if you don’t know what ⇌ means, read below: -

⇌(double head arrow) means reversible reaction).