Chemical, because it is breaking down the chemical and properties in the candle itself.
The CaCO3 produced if 47.5 moles of NH3 produced is calculated as follows
CaCN2 +3H2O = CaCO3 + 2NH3
by use of mole ratio between CaCO3 to NH3 which is 1:2 the moles of CaCO3 is therefore = 47.5 /2= 23.75 moles
mass of CaCO3 is therefore = moles x molar mass
= 23.75 moles x 100g/mol= 2375 grams which is approximate 2380 grams(answer 6)
Answer: B. Surface Tension
Explanation:
It is the tension of the surface film of a liquid caused by the attraction of the particles in the surface layer by the bulk of the liquid, which tends to minimize surface area.
The symbol of an isotope is:

A - the mass number
Z - the atomic number
X - the symbol of an element
The symbol of oxygen is O.
The atomic number is the same for all isotopes of one element. For oxygen it's 8, because every atom of oxygen has 8 protons in its nucleus.
The mass number is the number of nucleons (protons + neutrons) in the nucleus of an atom, and it's given in the name of an isotope. Oxygen-16 has the mass number 16, oxygen-17 has the mass number 17, oxygen-18 has the mass number 18.
Oxygen-16:

Oxygen-17:

Oxygen-18: