Methane is the limiting reactant because the other reactant is oxygen of the air which is always present in excess. Thus, the amounts of CO₂ and H₂O formed depend upon the amount of methane burnt.

160 has three significant figures while 160.0 has four significant figures.

Four.

(i) Reliability of measuring instrument.
(ii) Skill of the person making the measurement.

Molecular formula = (Empirical formula)_n
where n is positive integer.

This is due to the presence of dust particles.

According to Dalton's atomic theory, an atom is the ultimate particle of matter which cannot be further divided.

C₁₀H₈

Emphirical formula mass = CH₂O
= 12 + 2\(\times\)1 + 16
= 30 
Moleular mass = 180 
n = \( \frac{Molecular\ mass}{Emphirical\ formula\ mass}\)
= \(\frac{180}{30}\)
= 6
\(\therefore\)  Molecular formula = n\(\times\) Emphirical formula 
= 6\(\times\)CH₂O
= C₆H₁₂O₆

Law of conservation of mass and Avogadro's law because law of conservation of mass is simply the law of indestructibility of matter during physical or chemical changes.
Avogadro law states that equal volumes of different gases contain the same number of molecules under similar conditions of temperature and pressure.

The volume displaced by the pebble = 0.82 - 0.75 = 0.07 L = 70 mL,
Mass of the pebble = 150 g
Therefore, density of the pebble is
Density = \(\frac { Mass }{ Volume } \) = \(\frac { 150 }{ 70 } \) = 2.14 g mL^-1

\(2A+4B\longrightarrow 3C+4D\)
According to the given reaction, 2 moles of A rect with 4 moles of B.
Hence, 5 moles of A will react with 10 moles of
\(b\left( \frac { 5\times 4 }{ 2 } =10moles \right) \)
Limiting reagent decide the amount of product produced. According to the reaction, 4 moles of B produces 3 moles of C.
6 moles of B will produce\(\frac { 3\times 6 }{ 4 } =4.5\) moles of C.