Correct Answer: A. nuclear charge increases while the outermost electrons are drawn closer to the nucleus

Correct Answer: C) 1

Correct Answer: D) 6.9

Correct Answer: B) Sn

Explanation

(a)(i) It reacts with ammonia

(ii) It is a powerful bleaching agent

(iii) It combines with water to form HOCI and HCI acids

(b)(i) Displacement reaction

(ii) Redox reaction.

Correct Answer: D) The valence electrons of the elements increase progressively across the period

Correct Answer: B) ethene

Explanation

When you heat ethanol with concentrated sulfuric acid (H\(_2\)SO\(_4\) at a temperature of 180\(^{\circ}\)C, some of the ethanol molecules will lose a molecule of water (H\(_2\)O) and form a new compound. This process is known as dehydration. The question is asking which compound is formed in excess during this reaction when there is too much ethanol present. The options are ethane, ethene, ethanol, and ethoxyethane. To answer the question, we need to know which compound is formed when ethanol loses a molecule of water. The answer is ethene, which is a colorless gas with a sweet odor. This is because when ethanol loses a molecule of water, it forms a double bond between the two carbon atoms, resulting in the formation of ethene. Ethane, on the other hand, is a saturated hydrocarbon with the molecular formula C\(_2\)H\(_6\). It does not have a double bond between the carbon atoms. Ethanol is the starting compound in this reaction and will not be formed as a product. Ethoxyethane, also known as diethyl ether, is formed by the reaction between ethanol and sulfuric acid, but it is not the major product formed when excess ethanol is used. Therefore, the correct answer to the question is Option B: ethene.

Correct Answer: C) 0.280 dm³

Explanation

During the electrolysis of dilute tetraoxosulphate (VI) acid solution, also known as dilute sulfuric acid (H₂SO₄), the products formed are hydrogen gas at the cathode and oxygen gas at the anode. The balanced equation for the reaction at the anode is:

2H₂O(l) ? O₂(g) + 4H⁺(aq) + 4e^-

This equation tells us that 4 moles of electrons are required to produce 1 mole of oxygen gas. We are given that 0.05 moles of electrons were passed during the electrolysis.

To find the moles of oxygen gas produced at the anode, we can use the stoichiometric ratio:

\[\text{Moles of O}_2 = \frac{\text{Moles of electrons}}{4}\] \[\text{Moles of O}_2 = \frac{0.05}{4}\] \[\text{Moles of O}_2 = 0.0125\]

Now we can calculate the volume of gas produced at the anode using the molar volume of a gas at standard conditions (STP), which is 22.4 dm³ per mole:

Therefore, the volume of gas produced at the anode is0.280 dm³, which corresponds toOption C.

Correct Answer: B. concentrated tetraoxosulphate(VI) acid

Explanation

An alkene reacts with conc. H2SO4 to yield an alkyl hydrogen tetraoxosulphate (VI). The compound formed undergoes hydrolysis when boiled with water to yield an alcohol.

Explanation

(a) Graphite:-hexagonal: Diamond:-letrahedral/octahedral

(ii) Explain briefly why diamond is hard and a non-conductor of electricity while graphite is soft and an electrical conductor: n diamond each carbon atom is covalently bonded to four other carbon atoms forming an interlocking three dimens1onal network hence the hardness. Each of the four valence electrons is localized in a covalent bond hence there are no free mobile electrons, while in graphite each carbon atom is bonded to three other carbon atoms forming large sheets with van der Waal's force between the sheets which can easily slide over one another. One of the valence electrons of each atom is delocalized in a covalent bond and can act as a conductor of electricity OR Diamond is hard because it has a rigid/three-dimensional structure. It has no free/ mobile electrons hence it does not conduct electricity. Graphite has a layered structure held together by weak van der Waal's forces hence it is soft. It conducts electricity because it has free/ mobile electrons.

(bi) State what is Achieved at each of the Following Stages in the Purification of Water for Town Supply:

- Aeration- removes odor/kills bacteria.

- Screening- removal of suspended dirt

- Sedimentary- removal of suspended dirt particles after coagulation.

(ii) Name two Substances Responsible for Hardness in Water:

- Calcium hydrogen trioxocarbonate (IV).

- MagnesIum hydrogen triOxocarbonate(IV).

- Magnesium chloride.

- Magnesium tetraOxOSulphate( Vl).

- Calcium tetraoxosulphate (VI).

- Iron (lI) hydrogen trioxocarbonate(IV).

- Calcium chloride.

- Iron(Il) tetraoxosulphate(VI)

(iii) State two Methods for the Removal of Hardness in Water:

- By adding washing soda (Na\(_{2}\)CO\(_{3}\)). Adding (CaCOH)\(_{2}\) /lime water.

- Using ion-exchange resin / permutit/ zeolite.

- Boiling/ distillation

(iv) Give one Disadvantage of Hard Water:

- Furring of kettle/pipes causes blockage leading to power wastage/ scales in the boiler.

- Soap is wasted/ forms scums

- Cannot be used in dyeing/ tanning

- Not suitable for laundry.

- Not suitable for textile industry

(c) Describe Briefly the Extraction of Tin from its Ores:

(i) The ore is concentrated/crushed and washed with water, it is then roasted in air to remove impurities. The product is mixed with charcoal/carbon /coke and heated to reduce the oxide. it is then refined to obtain pure tin.

(ii) SnO\(_{2(s)}\) + 2C\(_{(s)\) \(\implies\) Sn\(_{(l)}\) + 2CO\(_{(g)}\)

(iii) (I) Sn\(_{(s)}\) + O2\(_{(g)}\) \(\implies\) Sn\(_{2(s)}\)

(II) Sn\(_{(s)\) + 2Cl\(_{2(g)}\) \(\implies\) SnCl\(_{4}\)