The substance which is a combination of different atoms is a compound.
Answer:
new Volume of gas=360L
Explanation:
Assume that given gas follow the ideality nature of gas
Assuming that temperature is constant;
P1 and V1 are the initial parameter of gas
and p2 and V2 are the parameter after increasing the pressure
according to boyle 's law pressure is inversly proportional to the volume at constant temperature.

given value of volume and gas
P1=90kPa
V1=600L
P2=150kPa
V2=?
After putting all values we get;
V2=360L
new Volume of gas=360L
N=9.03 x 10^ 23/6.02 x 10^23
n= 1.5 Mol
Answer: 35 g/cm
Explanation:
Density equals mass over volume. 525 divided by 15 is 35
Answer:
the size of Ca is the greatest ,then Mg is the greater on size than Be
Explanation:
if you make the electron configuration for each of the elements, what is the main difference u gonna see ?
Be 4 1s2/2s2
Mg 12 1s2 /2s2 2p6/3s2
Ca 20 1s2 /2s2 2p6/3s2 3p6 3d/4s2
see that all the elements are in the same group but are in different period
u gonna see the last electron valance shell in Ca are too far from its nucleus but in Be the last electrons are too close and more attracted to the atom's nucleus , so the size of Ca is the biggest then Mg then Be