Grade 10 : Science - 2. Acids/Bases (Set 7) | Concept of Maths

Question 1

A chemist mixes 50 mL of $0.1m HCl$ with 50 mL of $0.06m NaOH$. Calculate the final pH of the resulting solution at $25^\circ C$. (Assume $\log_{10}(2) \approx 0.30$)

Accepted Answer

B) $pH = 1.70$

Answer

A) $pH = 1.30$

Answer

C) $pH = 2.00$

Answer

D) $pH = 7.00$

Question 2

An amphoteric metal $M$ is treated with aqueous Sodium Hydroxide. A gas $G$ is evolved which burns with a pop sound, and a salt $S$ is formed. If metal $M$ is also used in the Thermite process for welding railway tracks, identify the chemical formula of salt $S$.

Accepted Answer

A) $NaAlO_2$

Answer

B) $Na_2ZnO_2$

Answer

C) $Al(OH)_3$

Answer

D) $Na_2FeO_4$

Question 3

A solution of a strong diprotic acid $H_2A$ has a concentration of 0.005 M. If this solution is diluted by a factor of 10, what will be the new pH of the solution?

Accepted Answer

C) $pH = 3.0$

Answer

A) $pH = 1.0$

Answer

B) $pH = 2.0$

Answer

D) $pH = 4.0$

Question 4

A sample of Blue Vitriol is heated strongly until it turns into a white powder $P$. If $P$ is then treated with a few drops of water, it turns blue again. What is the percentage by mass of water lost during the initial heating of 1 mole of Blue Vitriol? ($Cu=63.5, S=32, O=16, H=1$)

Accepted Answer

D) 36.1%

Answer

A) 18.0%

Answer

B) 25.2%

Answer

C) 30.1%

Question 5

In the Chlor-alkali process, a student observes that the gas evolved at the anode $X$ reacts with dry Slaked Lime to form a compound $Y$ used for disinfecting water. Identify $X$ and the chemical name of $Y$.

Accepted Answer

B) $X: Cl_2$, $Y: 	ext{Calcium Oxychloride}$

Answer

A) $X: H_2$, $Y: 	ext{Calcium Carbonate}$

Answer

C) $X: Cl_2$, $Y: 	ext{Calcium Hydroxide}$

Answer

D) $X: O_2$, $Y: 	ext{Bleaching Powder}$

Question 6

Consider four solutions P, Q, R, S with pH values of $2.2, 7.0, 1.0,$ and 13.5 respectively. Which of the following statements is mathematically correct regarding their Hydrogen ion concentration $[H^+]$?

Accepted Answer

C) $[H^+]$ of $R$ is 100 times that of $S$

Answer

A) $[H^+]$ of $P > [H^+]$ of $R$

Answer

B) $Q$ is more acidic than $P$

Answer

D) $[H^+]$ of $R$ is 10 times that of $P$ is false; it is actually more than 10 times.

Question 7

An organic acid $A$ found in ants reacts with Sodium Bicarbonate to release a gas $B$. Gas $B$ turns lime water milky. When $A$ is treated with Ethanol in the presence of an acid catalyst, a sweet-smelling compound $C$ is formed. Identify $A$.

Accepted Answer

A) Methanoic Acid

Answer

B) Ethanoic Acid

Answer

C) Citric Acid

Answer

D) Tartaric Acid

Question 8

What happens to the pH of water when $CO_2$ gas is bubbled through it?

Accepted Answer

C) pH decreases because $H_2CO_3$ is formed.

Answer

A) pH increases because $OH^-$ ions are formed.

Answer

B) pH remains 7 as $CO_2$ is neutral.

Answer

D) pH first increases then decreases.

Question 9

If the pH of a solution is 9, what is the concentration of Hydroxyl ions $[OH^-]$ at 298 K?

Accepted Answer

B) $10^{-5}m$

Answer

A) $10^{-9}m$

Answer

C) $10^{-7}m$

Answer

D) $10^{-14}m$

Question 10

Salt $X$ is used as an ingredient in antacids and also for making bread soft and spongy. On heating $X$, it decomposes to give salt $Y$ and a gas $Z$. $Y$ is further used in the manufacture of glass. Identify $X$ and $Y$.

Accepted Answer

A) $X: NaHCO_3, Y: Na_2CO_3$

Answer

B) $X: Na_2CO_3, Y: NaHCO_3$

Answer

C) $X: Ca(OH)_2, Y: CaCO_3$

Answer

D) $X: NaCl, Y: NaOH$