Answer: The final pressure is 75 mm Hg.
Explanation:
According to Boyle's law, at constant temperature the pressure of a gas in inversely proportional to volume.
Since, it is given that the temperature is constant. Hence, formula used is as follows.

Substitute the values into above formula as follows.

Thus, we can conclude that the final pressure is 75 mm Hg.
Answer:
Non-zero digits are always significant.
Any zeros between two significant digits are significant.
A final zero or trailing zeros in the decimal portion ONLY are significant. If a number ends in zeros to the right of the decimal point, those zeros are significant.
Explanation:
1.138 has 4 significant figures, which are 1, 1, 3 and 8. The numbers after the decimal point are decimals and are significant figures.
If it is just ratio you must just put the mass number on the either side of the symbol ‘:’ and cancel but the same process is not used to find simplest ratio
Mass is density times volume
0.760 x 531 = 403.56g
404g if 3 sig figs