Question

1. select the correct word or words given in the brackets.

(a) complete the following equation:
2koh + h₂so₄ ⟶? (kso₄+h₂o; k₂so₄+h₂o; kso₄+2h₂o; k₂so₄+ 2h₂o)
(b) which of the following compounds can form an aqueous solution of ph >7?
(carbon dioxide; hydrogen chloride; sodium chloride; sodium hydroxide)
(c) which of the following gases reacts with sulphuric acid to form a fertiliser?
(ammonia; carbon dioxide; hydrogen; nitrogen)
(d) a sample of pond water has a ph value of 11.
this means that the water is (weakly acidic; neutral; weakly alkaline; strongly alkaline).
(e) which of the following substances could be used in excess to change the ph of soil
from 5 to 7? (sodium chloride; calcium oxide; hydrochloric acid; sulphuric acid).

1. fill in the blanks with a suitable word or phrase or numerical value with unit as necessary.

(a) the combination of h⁺ and oh⁻ ions to form water is called ______.
(b) the ph of alkali solution is greater than ______.
(c) solutions having ph values below 4.5, turn blue litmus paper ______.
(d) a measure of the acidity or alkalinity of a solution is known as ______.
(e) the salt can be classified as soluble and insoluble salts depending on the types of
______.
(f) sodium citrate is a soluble salt. it is used as a food ______.

1. complete the following sentences by using the words given below:

(a) base, dissolves, hydrogen, ions, proton
when an acid ____ in water, hydrogen __are formed. a ____ ion is a proton.
an acid is a____ donor. it gives its proton to a ____.
(b) hydroxides, hydrogen, dissolves, salt, oxides, water
an acid is a compound that ____in water to produce ____ions. acids react with
metals to form ____and hydrogen. when acids react with metal __ or ____,
a salt and ______are formed.
(c) acids, ammonia, hydroxide, salt, soluble
alkalis are water ____ bases. examples of alkalis are__ and sodium ____.
alkalis react with____ to form a ____and water.
(d) universal, alkaline, neutral, high, scale, seven, acidic
the ph____ shows how acidic or __a solution is. strongly____ solutions
have a low ph, strongly alkaline solution have a ______ ph. a solution that is neither
acidic nor an alkaline is called a____ solution. it has a ph of ____. the ph of
a solution can be measured using ______indicator or a ph meter.

Explanation:

Question 2(a)

Step1: Identify reaction type

This is a neutralization reaction (acid + base → salt + water). The acid is $\ce{H_{2}SO_{4}}$ (sulfuric acid), the base is $\ce{2KOH}$ (potassium hydroxide).

Step2: Balance the reaction

• For potassium ($\ce{K}$): 2 moles of $\ce{KOH}$ give 2 $\ce{K^+}$ ions, so the salt should have 2 $\ce{K^+}$, forming $\ce{K_{2}SO_{4}}$ (potassium sulfate).
• For water: 2 moles of $\ce{OH^-}$ from $\ce{2KOH}$ react with 2 moles of $\ce{H^+}$ from $\ce{H_{2}SO_{4}}$ (since $\ce{H_{2}SO_{4}}$ has 2 $\ce{H^+}$) to form $\ce{2H_{2}O}$.

So the balanced equation is $\ce{2KOH + H_{2}SO_{4} -> K_{2}SO_{4} + 2H_{2}O}$.

• Carbon dioxide ($\ce{CO_{2}}$) dissolves in water to form carbonic acid ($\ce{H_{2}CO_{3}}$), so solution is acidic (pH < 7).
• Hydrogen chloride ($\ce{HCl}$) dissolves in water to form hydrochloric acid, acidic (pH < 7).
• Sodium chloride ($\ce{NaCl}$) is a neutral salt, solution has pH = 7.
• Sodium hydroxide ($\ce{NaOH}$) is a strong base, dissociates to give $\ce{OH^-}$ ions, so solution is alkaline (pH > 7).

• Ammonia ($\ce{NH_{3}}$) is a base. It reacts with sulfuric acid ($\ce{H_{2}SO_{4}}$) to form ammonium sulfate ($\ce{(NH_{4})_{2}SO_{4}}$), which is a fertilizer (provides nitrogen for plants).
• Carbon dioxide reacts with sulfuric acid? No, $\ce{CO_{2}}$ is an acid anhydride, doesn't react to form fertilizer.
• Hydrogen and nitrogen don't react with sulfuric acid to form fertilizers.

Answer:

$\ce{K_{2}SO_{4} + 2H_{2}O}$

Question 2(b)