Dhoran 6 Samajik Vigyan Ekam Kasoti December 2021 Paper Solution

(i) Explain why is hydrochloric acid a strong acid and acetic acid, a weak acid ? How can it be verfied ? (ii) Explain why equeous solution of an acid conducts electricity. (iii) You have four solutions A, B,C and D. The pH of solution A is 6, B is 9, C is 12 and D is 7. (a) Identify rhe most acidic and most basic solutions. (b) Arrange the above four solutions in the increasing order of H^(+) ion concentration. (c ) State the change in colour of pH paper on dipping in solution C and d.

You have four solutions A, B, C and D. The pH of solution A is 6, B is 9, C is 12 and D is 7. (a) Identify the most acidic and most basic solutions. (b) Arrange the above four solutions in the increasing order of H^+ ion concentration. (c) State the change in colour of pH paper on dipping in solution C and D.

(a) A gas is produced when conc. H_(2)SO_(4) is added to solide sodium chloride taken in a test tube and the tube is heated. The gas coming out through the delivery tube is passed over a dry litmus paper and then over a moist litmus paper. What would you observe ? Explain your answer. (b) Fresh mikl has pH of 6. When it changes to curd (yogurt(, will its pH value increase or decrease? Why ? (c ) What will be the colour of blure limus in a solution of sodium carbonate ?

(i) Four samples A, B, C and D change the colour of pH paper or solution to Green, Reddish-pink, Blue and Orange. Their pH was recorded as 7, 2, 10.5 & 6 respectively. Which of the samples has the highest amount of Hydrogen ion concentration? Arrange the four samples in the decreasing order of their pH. (ii) Rahul found that the Plaster of Paris, which he stored in a container, has become very hard and lost its binding nature. What is the reason for this? Also, write a chemical equation to represent the reaction taking place (iii) Give any one use of Plaster of Paris other than for plastering or smoothening of walls.

Amongst the following, the total number of compounds whose equesous solution turns red litmus paper blue is: {:(NaCN,KCl,CH_(3)COONH_(4),NaH_(2)PO_(4),ZnCl_(2), Na_(3)PO_(4)),(Fe(NO_(3))_(3),Na_(2)CO_(3),NH_(4)Cl,NaHCO_(3),Na_(2)C_(2)O_(4),Na_(2)HPO_(4)):} Given: {:("Acid",ka_(1),ka_(2),ka_(3)),(H_(3)PO_(4),10^(-3),10^(-8),10^(-12)),(H_(2)CO_(3),10^(-6),10^(-11),-),(H_(2)CO_(3),10^(-2),10^(-5),-):}