Answer: (C) conservation of matter
Solution: Law of conservation of matter or mass states that' total mass of the reactants should always be equal to the total mass of the product that is the total mass is remained conserved in a chemical reaction.
A balanced chemical equation always follow this law.
For example:

Mass of hydrogen = 1 g/mol
Mass of Oxygen = 16 g/mol
Total mass on the reactants = 2(2×1)+(2×16)= 36g/mol
Total mass on the product side = 2[(2×1) +16] = 36 g/mol
As,
Mass on reactant side = Mass on the product side
Therefore, a balanced chemical reaction follows Law of Conservation of mass.
The sun makes the moisture go into the air and evaporate
The number of protons in the nucleus for that element
Answer:
The correct answer is option b, that is, 2.1 M Na₃PO₄.
Explanation:
The solution with the largest concentration of ions will possess the highest conductivity.
a) 3.0 M NaCl
NaCl ⇔ Na⁺ + Cl⁻
Here the total number of ions is 2, therefore, the concentration of ions is 3.0 × 2 = 6.0 M
b) 2.1 M Na₃PO₄
Na₃PO₄ ⇔ 3 Na⁺ + PO₄³⁻
Here the total number of ions i 4. Therefore, the concentration of ions is
2.1 × 4 = 8.4 M.
c) 2.4 M CaCl₂
CaCl₂ ⇔ Ca²⁺ + 2Cl⁻
The total number of ions is 3. Therefore, the concentration of ions is
2.4 × 3 = 7.2 M
d) 3.2 M NH₄NO₃
NH₄NO₃ ⇔ NH₄⁺ + NO₃⁻
The total number of ions is 2. The concentration of ions will be,
3.2 × 2 = 6.4 M
Hence, the highest conductivity will be of 2.1 M Na₃PO₄.