ACIDS, BASES AND SALTS

HOTS: (High Order Thinking Skill) Questions

1. Kazi and priyam want to prepare dil H2SO4 .Kazi added conc.H2SO4 to water
slowly with constant stirring& cooling whereas Priyam added water to conc.
H2SO4.Name the student who was correct and why?
2. A compound X is bitter in taste. It is a component of washing powder& reacts
with dil.HCl to produce brisk effervescence due to colourless, odourless gas
Y which turns lime water milky due to formation of Z. When excess of CO2
is passed, milkiness disappears doe to formation of P. Identify X, Y, and Z &
P.
3. Compound P forms enamel of teeth. It is the hardest substance of the body.
It does not dissolve in water but it is corroded when pH in the mouth is below
5.5. How does tooth paste prevent dental decay?
4. The oxide of a metal M was water soluble when a blue litmus strip was
dipped in this solution, it did not go any change in colour. Predict the nature
of oxide
5. A first aid manual suggests that vinegar should be used to treat wasp sting
and baking soda for bee stings.
(i) What does this information tell you about the chemical nature
of the wasp stings
(ii) If there were no baking soda in the house, what other household
substance could you use to treat bee stings?
6. `A` is a soluble acidic oxide and `B` is a soluble base. Compared to pH of
pure water. What will be the pH of (a) solution of A (b) solution of B?
7. A road tanker carrying an acid was involved in an accident and its contents
spilled on the road. At the side of the road, iron drain covers began melting
and fizzing as the acid ran over them. A specialist was called to see if the
acid actually leaked into the nearby river.
(a) Explain how the specialist could carry out a simple test to see if the
river water contains some acid or not.
(b) The word melting is incorrectly used in the report. Suggest a better
name that should have been used.
(c) Explain why drain covers began fizzing as the acid rain over them.
8. A compound `X` on electrolysis in aqueous solution produces a strong base.
`Y` along with two gases `A` and `B`. `B` is used in manufacture of
bleaching powder. Identify X, Y, A and B. Write chemical equations.
9. A yellow powder X gives a pungent smell if left open in air. It is prepared by
the reaction of dry compound Y with chlorine gas. It is used for disinfecting
drinking water. Identify X and Y. and write the reaction involved.
10. When CO2 gas pass through saturated solution of ammonical brine, two
compound `X` and `Y` are formed. `Y` is used as antacid and decomposes to
form another solid `Z`. Identify `X`,`Y`, `Z` and write chemical equations.
11.A compound `A on heating at 370 K gives `B` used as plaster for supporting
fractured bones in the right position. `B` on mixing with water changes to `A`.
Identify `A` and `B` and write the chemical reaction.
12. A few drops of phenolphthalein indicator were added to an unknown solution
A. It acquired pink colour. Now another unknown solution B was added to it
drop by drop and the solution becomes colorless. Predict the nature of A & B.
13. A student heated a few crystals of copper sulphate in a dry boiling tube.
(a) What will be the color of the copper sulphate after heating?
(b) Will you notice water droplets in the boiling tube?
(c) Where have these come from?
14. A substance `X` used in the kitchen for making tasty crispy pakoras.and is also an
ingredient of antacid. Name the substance `X`.
(i) How does `X` help to make cakes and bread soft and spongy.
(ii) Is the pH value of solution of `X` is lesser than or greater than 7.0?