Correct Answer: D. Sodium chloride

Correct Answer: B)

Pb\(^{2+}\)

Explanation

This question is asking about two solutions, X and Y, and their reactions with silver nitrate (AgNO\(^3\)). When solution X is mixed with AgNO\(^3\) solution, it gives a white precipitate. The precipitate is soluble in NH\(^3\). When solution Y is added to X, a white precipitate is also formed. However, this precipitate is soluble on boiling. The question then asks which of the given options is present in solution Y. The options are Ag\(^+\), Pb\(^{2+}\), Pb\(^{4+}\), and Zn\(^{2+}\). The correct answer is option B, Pb\(^{2+}\). The fact that the white precipitate formed in solution Y is soluble on boiling suggests that it is not Ag\(^+\), which would not dissolve upon boiling. Pb\(^{4+}\) is an unlikely option, as it is a highly oxidizing agent and is not commonly found in solutions. Zn\(^{2+}\) is also unlikely, as it does not form a white precipitate with AgNO\(^3\) solution. Therefore, the correct answer is option B, Pb\(^{2+}\). This suggests that solution Y contains Pb\(^{2+}\) ions, which react with the AgNO\(^3\) solution to form the white precipitate. To learn more about this, please read the relevant sections of the recommended textbooks.

Correct Answer: D. Hematite

Explanation

Hematite is the principal ore of iron and is widely mined for the extraction of iron metal.

Correct Answer: C) evaporation

Explanation

Evaporation is the process of a substance in a liquid state changing to a gaseous state due to an increase in temperature and/or pressure. Evaporation is a fundamental part of the water cycle and is constantly occurring throughout nature.

Correct Answer: B)

C\(_6\)H\(_5\)COOH + CaO \(\rightarrow\) C\(_6\)H\(_6\) + CaCO\(_3\)

Explanation

The correct reaction among the given options is:

Option B: C\(_6\)H\(_5\)COOH + CaO \(\rightarrow\) C\(_6\)H\(_6\) + CaCO\(_3\)

This reaction is an example of a reaction between an organic acid and a metal oxide. In this case, benzoic acid (C\(_6\)H\(_5\)COOH) reacts with calcium oxide (CaO) to form benzene (C\(_6\)H\(_6\) and calcium carbonate (CaCO\(_3\).

When an organic acid reacts with a metal oxide, the hydrogen (H) from the acid combines with the oxygen (O) from the metal oxide to form water (H\(_2\)O), and the remaining parts of the molecules combine to form a new compound. In this case, the hydrogen from benzoic acid and the oxygen from calcium oxide combine to form water, which then evaporates, leaving behind benzene and calcium carbonate.

It is important to note that the other options presented do not represent correct reactions, either because the products do not match the reactants or because the reactions do not follow the expected patterns for the given reactants.

Correct Answer: D. 4,2,1

Correct Answer: D) 450 cm³

Explanation

In this question, we are given information about the reaction between excess hydrochloric acid (HCl) and limestone, as well as the neutralization of the unreacted acid with potassium carbonate (K\(_2\)CO\(_3\). The question asks us to determine the original volume of the acid. To solve this problem, we first need to write out the balanced chemical equation for the reaction between HCl and limestone: CaCO\(_3\) + 2HCl ? CaCl\(_2\) + CO\(_2\) + H\(_2\)O This equation tells us that one mole of CaCO\(_3\) reacts with two moles of HCl. Since we are given an excess of HCl, we can assume that all of the CaCO\(_3\) has reacted. We are also given the mass of the CaCO\(_3\) (2g) and its molar mass (100 g/mol), so we can calculate the number of moles of CaCO\(_3\) using the formula: moles = mass/molar mass moles of CaCO\(_3\) = 2g/100 g/mol = 0.02 mol Since one mole of CaCO\(_3\) reacts with two moles of HCl, we know that 0.04 moles of HCl were required to react with the CaCO\(_3\). However, we are told that there is unreacted HCl remaining, which requires 25 cm\(^3\) of 0.10 moldm\(^{-3}\) K\(_2\)CO\(_3\) to neutralize it. This information allows us to calculate the number of moles of HCl that were not used in the reaction with CaCO\(_3\): moles of HCl = concentration x volume moles of HCl = 0.10 moldm\(^{-3}\) x 0.025 dm\(^3\) = 0.0025 mol To find the original volume of the acid, we need to add the volume of the unreacted HCl to the volume of HCl that was used in the reaction with CaCO\(_3\): original volume of HCl = (moles of HCl used in reaction + moles of unreacted HCl)/concentration original volume of HCl = (0.04 mol + 0.0025 mol)/0.10 moldm\(^{-3}\) = 0.425 dm\(^3\) = 425 cm\(^3\) Therefore, the correct answer is Option D: 450 cm\(^3\).

Correct Answer: B) bacteria

Explanation

(a)(i) I Biotechnology is the use of biological processes / living organisms to make products for human use.

II. Biogas is a fuel obtained from organic waste through the process of anaerobic decomposition

(ii) Production of drugs (medical), fertilizer, waste management, production of kenkey, fufu, gars, burukutu / any food or beverage produced from fermentation (domestic), industrial application, etc

(b)(i) — Add yeast to cane sugar and leave to stand (at room temperature)

— Enzyme sucrose hydrolyse / converts

— Enzyme zymase ferments / converts glucose to ethanol and CO\(_2\)

— Mixture is distilled to obtain ethanol.

ii) Carbon IV oxide

(iii) — In aerated drinks

— as fire extinguisher

— coolant / refrigerant

— solvay process

— synthesis of Na\(_2\)CO\(_3\)

iv) Ethanol from cane sugar is renewable because It is from plants which can be cultivated continuously Ethanol from petroleum is non-renewable because it is from a sou;-c,o, which can get exhausted. Heavy chemicals are chemicals used extensively in industries and are produced in very large quantities. Fine chemicals are chemicals produced in small quantities for specific purposes and to a very higil degree of purity. Heavy chemicals — H\(_2\)SO\(_4\), NaOH, NH\(_3\), CaCO\(_3\), HNO\(_3\), HCI, NaCO\(_3\) bleaching powder, metals (iron, tin, aluminium, Copper, Zinc).

Fine chemicals — laboratory / analytical reagents, drugs, dyes, perfumes, photographic reagents, additives, cosmetics.

d) O\(_2\), C\(_{12}\)HCI increasing order to deviation The extent of deviation depends on intermolecular forces. HCI is a polar and will have a greater intermolecular attraction than Oxygen and Chlorine. The molar mass of chlorine is greater than that of oxygen hence stronger van der waals forces than oxygen

Correct Answer: C. 18