I don't know what the problem is, but here are some rues to help you out:
- All non-zero figures are significant
- When a zero falls between non-zero digits, that zero is significant.
- When a zero falls after a decimal point, that zero is significant.
- When multiplying and dividing significant figures, the answer is limited to the number of sig figs equal to the least number of sig figs in the problem.
- When adding and subtracting, the answer is limited to the number of decimal places in the number with the least number of decimal places.
Answer:
A) 122 atm
Explanation:
PV = nRT
Solve for P --> P = nRT/V
n = 10.0 mol + 5.0 mol = 15.0 mol
R = 0.08206 L atm / mol K
T = 25 + 273 = 298 K
V = 3.0
P = (15.0)(0.08206)(298) / (3.0) = 122 atm
Answer:
B) K2X
Explanation:
In an uncharged compound, the total oxidation state must be zero. The oxidation state of the calcium is +2, thus we get the following formula, where x is the oxidation state of the polyatomic ion X:

Also, it is known that potassium has an oxidation state of +1. Since the new compound also has a total oxidation state equal to zero, we get the following equation, where k is the number of K atoms:

That's how it is found that the compumd consists of 2 K+ ions and one X ion.
The 3rd option is the answer
An Ionic bond is when you have a metal and a nonmetal element bonded together. In this kind of bonds, the metal atom takes electrons from the nonmetal. on other words, this bond involves the gaining and losing of electrons. The atom that receives the electrons becomes an anion (negatively charged ion) and the one that loses them becomes the cation (positively charged ion)
A covalent bond is a bond created between two nonmetals element. In here, both atoms share the electrons.
Both bonds involve interaction between atoms.