Acids Bases and Salts Test - 18

Acids generally taste sour due to the sour H⁺ ion; bases taste bitter due to the OH^- ion; but they may have other tastes depending on the other part of the molecule. Bases are usually soapy in nature.

In the given options only baking soda is basic in nature so it will taste bitter. 

Hence, option (A) is correct.

When one equivalent of an acid and one equivalent of a base is  mixed then they form water and a salt. Heat is evolved in this process called heat of neutralization so the temperature of the system increases. ie. temperature of the system increases due to heat release. 

Hence, option (C) is correct. 

When we white-wash the walls, then first calcium oxide is made to react with water to form calcium hydroxide. The calcium hydroxide is then applied to the walls, which slowly reacts with the carbon dioxide gas present in air to form a thin shining layer on the walls.

Ammonium hydroxide is  widely used as a cleaning and bleaching agent.

Soaps are sodium or potassium salts of long chain fatty acids. When triglycerides in fat/oil react with aqueous NaOH or KOH, they are converted into soap and glycerol.Since this reaction leads to the formation of soap, it is called the Saponification process.

Antacids are a class of medicines that neutralize acid in the stomach. Since, Mg(OH)₂ is basic in nature so it is used as the antacids. eg; milk of magnesia.

Hence, option (D) is correct. 

Litmus paper is an indicator which gives us information about acidic and basic solutions by changing its colour. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or alkaline conditions. So it will change into a blue colour in the soap solution (basic solution). 

Phenolphthalein is used as an indicator in acid–base titrations. For this application, it turns colorless in acidic solutions and pink in basic solutions. So phenolphthalein will be changed into pink colour in the soap solution.

Turmeric is an indicator for acidity and basicity. Turmeric is yellow in acid and neutral substances, but turns bright red/reddish brown with bases. So turmeric will give a reddish brown colour to the soap solution.

Hence option (B) is correct.

Calamine solution is applied on the skin when an ant bites. When an ant bites, it injects formic acid into the skin. Calamine solution contains zinc carbonate which is basic in nature. So the basic nature of calamine neutralizes the formic acid injected by the ant. Hence, calamine is acting like an antacid. 

Hence, option (C) is correct.

Litmus paper is an indicator which gives us information about acidic and basic solutions by changing its color. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or alkaline conditions.

In the question, Since, liquid present in the beaker turned litmus into red colour so it must be an acidic solution. 

Hence, option (D) is correct.

Acetic acid is present in the vinegar.

Citric acid is present in the orange and lemon hence, they are called citrus fruit. 

Lactic acid is present in curd that is formed by the activity of bacteria lactobacillus.

Tartaric acid is present in the grapes. 

Hence, option (C) is correct. 

Acids generally taste sour due to the sour H⁺ ion; bases taste bitter due to the OH^- ion. Since, Person labelled the solution as the base so the solution must be bitter in taste. 

Hence option (D) is the correct answer. 

Litmus paper is an indicator which gives us information about acidic and basic solutions by changing its color. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or alkaline conditions.

Litmus paper does not change its colour in the neutral medium.

Since water is a neutral molecule so litmus paper will not change its colour.

Hence, option (C) is correct. 

Since, Unknown solution in the test tube 'A' turns pink on addition of the indicator, but no colour change is observed in the test tube 'B'. also each option is supposing test tube ‘A’ as soap solution (basic nature) and test tube ‘B’ as vinegar (acidic nature). So we should select that indicator which has pink colour in the basic condition and no colour in the acidic condition ie. phenolphtaleine. 

Note:  Phenolphthalein is used as an indicator in acid–base titrations. For this application, it turns colorless in acidic solutions and pink in basic solutions.

Hence, option (C) is correct. 

Milk of magnesia, common name for the chemical compound magnesium hydroxide, Mg(OH)₂ is used as the antacids. Milk of magnesia is an alkaline suspension, meaning that it will cause neutralization when it encounters anything acidic. This is why it makes an excellent antacid, as it neutralizes excess stomach acid when swallowed. Milk of Magnesia is also used as an antacid to relieve indigestion, sour stomach, and heartburn.

Hence, option (D) is correct.

Indicators are substances whose solutions change colour due to changes in pH. These are called acid-base indicators as they show different colour in acidic and basic mediums. 

Hence, option (A) is correct. 

Litmus paper is an indicator which gives us information about acidic and basic solutions by changing its color . Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or alkaline conditions.

To change red litmus paper into blue colour, the solution must be basic . In the given question only option (A) is basic. 

Lemon , vinegar, curd are acidic in nature as they contain citric acid , acetic acid and lactic acid respectively. So these all convert blue litmus paper into red but have no effect on red litmus paper. 

Hence, option (A) is correct. 

Turmeric is an indicator for acidity and basicity. Turmeric is yellow in acid and neutral substances, but turns bright red with bases. 

Since soaps are basic in nature, when  a turmeric stain on a white cloth turns red, when washed with soap. 

Note: Soaps are sodium or potassium salts of long chain fatty acids. When triglycerides in fat/oil react with aqueous NaOH or KOH, they are converted into soap and glycerol.

Hence, option (C) is correct. 

Turmeric is used as a spice in the food and is known to have an excellent healing quality.

In chemistry laboratories it is used as an indicator for acidity and basicity as it changes its colour in different mediums. Turmeric is yellow in acid and neutral substances, but turns bright red with bases.

Hence, option (C) is correct.