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 air pressure inside the can is lower compared to that of outside air pressure.
Explanation:
- In general, the air pressure of an already opened can will be the same as the outside pressure.
- Since the can is evacuated and remain as vacuum, so there will be no pressure difference in it.
- If the can opens, air inside the can push the top and escapes to the outside.
- This is due to high pressure experienced outside the can compare to that of lower pressure inside the can and this may even cause can to collapse itself.
Answer:
4
Explanation:
Carbon configuration- 2,4
Valence electrons means the outershell electrons
That means valence electrons=4
Einstein's famous equation, E = mc^2 relates the mass (m) of an object to energy (E). The speed of light (c), is the constant of proportionality. Einstein formulated the equation within his theory of special relativity. Indeed, a physical interpretation of this equation is that any given mass is equivalent to the energy given by the equation, if it were suddenly converted to energy. Therefore the answer to the question is true.