First, we determine the number of moles of barium phosphate. This is done using:
Moles = mass / Mr
Moles = 1 / 602
Moles = 0.002
Now, we see from the formula of the compound that each mole of barium phosphate has 2 moles of phosphorus (P). Therefore, the moles of phosphorus are:
0.002 * 2 = 0.004
The number of particles in one mole of substance is 6.02 x 10²³. The number of phosphorus atoms will be:
0.004 * 6.02 x 10²³
2.41 x 10²¹ atoms of phosphorus are present
Water is the only one of these that would work by process of elimination.
The answer is 6.1*10^-3 atm.
The pictures and explanations are there.
Hey there!
Molar mass N2 = 28.01 g/mol
Therefore:
28.01 g N2 -------------- 6.02*10²² molecules N2
( mass N2 ?? ) ----------- 25,000 molecules N2
mass N2 = ( 25,000 * 28.01 ) / ( 6.02*10²³ )
mass N2 = 700250 / 6.02*10²³
mass N2 = 1.163*10⁻¹⁸ g
Hope that helps!
Answer : The correct options are,
(B) 
(C) 
Explanation :
Boyle's Law : It is defined as the pressure of the gas is inversely proportional to the volume of the gas at constant temperature and number of moles.

or,

The relation between the pressure and volume of two gases are:

where,
= initial pressure of gas
= final pressure of gas
= initial volume of gas
= final volume of gas