Which of the following is a mixture? A. Sugar B. Seawater C. Sodium chloride D. Iron filings. What is the relative atomic mass of element Z if it has two isotopes, one making up 90% with mass 16 and t

$$
\text{Relative Atomic Mass} = (\% \text{abundance of isotope 1} \times \text{mass of isotope 1}) + (\% \text{abundance of isotope 2} \times \text{mass of isotope 2})
$$
$$
\text{Relative Atomic Mass} = (0.90 \times 16) + (0.10 \times 18)
$$
$$
\text{Relative Atomic Mass} = 14.4 + 1.8
$$
$$
\text{Relative Atomic Mass} = 16.2
$$
B. $\boxed{\text{16.2}}$

8. Local black soap is produced through saponification, a process where fats or oils (like palm oil) react with an alkali (base) to form soap and glycerol. The ash extract provides the necessary alkali (e.g., potassium carbonate) for this reaction. C. alkali

9. Propan-1-ol is a primary alcohol. Complete oxidation of a primary alcohol first yields an aldehyde (propanal), and then further oxidation yields a carboxylic acid. Therefore, complete oxidation of propan-1-ol gives propanoic acid. D. propanoic acid

10. When water is added to calcium carbide ($\text{CaC}_2$), it produces acetylene gas ($\text{C}_2\text{H}_2$). Acetylene is a hydrocarbon that burns with a characteristic bright, sooty flame due to incomplete combustion, which is known as a luminous flame. A. luminous flame