Solution,
Mass of Mg - 21gm
molar mass of Mg - 24gm
moles = Given mass/ Molar mass
moles = 21/24 = 0.875
1 mole of Mg produce 1 mole of H2 gas
so 0.875 mole of Mg will produce 0.875 moles of H2 gas
One mole of H2 gas = 22.4 litre
0.875 mole of H2 gas = 0.875×22.4
0.875 mole of H2 gas = 19.60 litre
So the nearest ANSWER is Option four 19.37 litre.
Answer : The number of moles of gas present in container are 1.697 mole.
Explanation :
Using ideal gas equation,

where,
P = pressure of gas = 74 mmHg = 0.097 atm
conversion used : (1 atm = 760 mmHg)
V = volume of gas = 500.0 L
T = temperature of gas = 
n = number of moles of gas = ?
R = gas constant = 0.0821 L.atm/mole.K
Now put all the given values in the ideal gas equation, we get the number of moles of gas in the container.


Therefore, the number of moles of gas present in container are 1.697 mole.
Answer:
Answer below!!
Explanation:
The volume of a gas is inversely proportional to presure keeping the temperature the same.
Hope I helped!!!
:)
Answer: D. Series circuits are simpler than parallel circuits.
Explanation:
In series circuit, all the components are connected in single path of current flow.
If one part of the circuit breaks, complete circuit would break and all the other parts also would not operate.
The voltage is not same everywhere. It is different across each component.
In series circuit, net resistance is more as resistance of all the components connected in series are added up.
So, the only advantage of a series circuit is that is simpler than the parallel circuits. Thus, the correct option is D.
Becuz the sun refelt off the earth and on to the moon.