Answer:

Explanation:
We already know that the mass number of an atom is the sum of the number of protons and the number of neutrons.
So, the mass number of this isotope is;
Number of protons = 7
Number of neutrons = 8
Mass number = 7 + 8 = 15
Hence, the isotope is;

Answer:
Halogens family
Explanation:
Be familiar with the periodic table
The answer will be 12 nitrogen or N2 will be produced because if you changed the coefficient to 12 on the reactant side and distribute, the nitrogen would be 12 when distributed and what happens on one side has to equal to the other side, which is the product side.
Icy water is just water.
It is a compound.
Answer:
1. b
2. a
Explanation:
1. The density of an object represents the mass per unit volume of the object. A density of 0.45 g/mL means that 1 mL of the object weighs 0.45 g, 1.000 g/mL means 1 mL weighs 1 g, etc.
<u>A density of 35,885 g/mL means that 1 mL of the object weighs 35,885 g. This is a ridiculously high amount of weight for an object with a volume of 1 mL and seems not reasonable. It is highly unlikely that such a substance exists in nature.</u>
2. <u>Considering the fact that only rock would sink in water of all the substances from a - d, it thus means that rock would have the greatest density.</u> Oil, oxygen, and ice will all float on water, meaning that they are less dense than water.