Effect on Indicators by Acids and Bases

Q.

Olfactory indicators with examples and their changes when react with acid or base

Q.

What is an indicator?

Q. What will be the action of the following substances on litmus paper?​

Dry $\text{HCl}$ gas, Moistened ${\text{NH}}_3$ gas, Lemon juice, Carbonated soft drink, Curd, Soap solution.

Q.

What do all acids and bases have in common?

Q.

What is the colour of the flame of sodium and potassium?

Q.

Explain physical and chemical properties of copper.

Q.

What is the colour change observed in dil. HCl solution when phenolphthalein is added to it?

1. Pink
2. Green
3. Colourless
4. Yellow

Q.

The indicators which turn red in acid solution are :

(a) turmeric and litmus

(b) phenolphthalein and methyl orange

(c) litmus and methyl orange

(d) phenolphthalein and litmus

Q. In what condition do vanilla, onion and clove lose their smell?

1. Neutral
2. Never
3. Acidic
4. Basic

Q.

Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.

How will she find the nature of the gas?

Q.

A solution turns phenolphthalein indicator pink. The most likely pH of this solution will be :

(a) 6

(b) 4

(c) 9

(d) 7

Q.

Question 17.
Which one of the following can be used as an acid-base indicator by a visually impaired student?
(a) Litmus
(b) Turmeric
(c) Vanilla essence
(d) Petunia leaves

Q.

Pratyush took a sulfur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in the figure below.

(a) What will be the action of gas on (i) dry litmus paper? (ii) moist litmus paper?

(b) Write a balanced chemical equation for the reaction taking place.

Q. Why do acids change litmus paper colour from blue to red while bases don't?

Q. Identify the olfactory indicators from the given options.

1. Vanilla
2. Clove
3. Onion
4. Turmeric

Q.

What happens when cupric oxide reacts with sulphuric acid?

1. Copper sulphide is formed

2. Copper sulphate is formed

3. Copper hydroxide is formed

4. None of these

Q.

The name of the product formed in the reaction of sulphur and Oxygen is sulphur dioxide gas. When sulphur dioxide is dissolved in water, sulphurous acid is formed. The sulphurous acid turns blue litmus paper to red. Generally, oxides of non-metals are acidic in nature.

Questions maybe

(i) Which gas is formed when sulphur reacts with oxygen?

(ii) What is the nature of oxides of non-metals?

Q. (a) Define an indicator.
(b) Explain, why a universal indicator is preferred to acid-base indicators.

Q. Colour of Methly Orange in Neutral Solutions
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Q.

What is the colour of Ferric hydroxide?

Q.

Generally, metallic oxides are basic and non-metallic oxides are acidic in nature. The solution of which of the following oxides in water will change the color of blue litmus to red?

1. Sulfur dioxide

2. Magnesium oxide

3. Iron oxide

4. Copper oxide

Q. A student prepared solutions of $\text{(i)}$ an acid $\text{(ii)}$ a base in two separate beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since both the solutions are colourless how will she distinguish between the two?​

Q. Question 28.
Which of the following statement is true for acids?
(a) Bitter and change red litmus to blue
(b) Sour and change red litmus to blue
(c) Sour and change blue litmus to red
(d) Bitter and change blue litmus to red

Q.

Describe an experiment to study a neutralization reaction.

Q.

Name an indicator which is red in acid solution but turns blue in basic solution.

Q.

Amongst dry HCl and HCl solution , which can show acidic properties

Q.

The indicator which produces a pink colour in an alkaline solution is :

(a) methyl orange

(b) turmeric paper

(c) phenolphthalein

(d) litmus paper

Q.

(a) What is an indicator ? Name the three common indicators.

(b) Name an acid-base indicator extracted from lichen.

(c) What colour does the turmeric paper turn to when put in an alkaline solution ?

Q.

When a solution is added to vanilla extract, then the characteristic smell of vanilla cannot be detected. State whether the given solution is an acid or a base.

Q.

What will be the action of the following substances on litmus paper?

Dry $\mathrm{HCl}$ gas, Moistened ${\mathrm{NH}}_3$ gas, Lemon juice, Carbonated soft drink, Curd, Soap solution.