Question

(iv) Three beakers labelled as A, B and C each containing 25 mL of water was taken. A small amount of NaOH,
anhydrous CuSO, and NaCl were added to the beakers A, B and C respectively. It was observed that there
was an increase in the temperature of the solutions contained in beakers A and B, whereas in case of beaker
C, the temperature of the solution falls. Which one of the following statement(s) is (are) correct?
(i) In beakers A and B, exothermic process has occurred.
(ii) In beakers A and B, endothermic process has occurred.
(iii) In beaker C, exothermic process has occurred.
(iv) In beaker C, endothermic process has occurred.
(a) (i) only
(b) (ii) only
(c) (i) and (iv)
(d) (ii) and (ii)
1
were left for the elements to be discovered later. Which of the following​

Answer 1

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Concept: When heat is released (Exothermic process) surrounding gets warm means temperature rises. 

When heat is absorbed (Endothermic process) surrounding gets cold means temperature falls.

In beaker A:

NaOH+H2O→Na++OH−+H2O+heat 

In beaker B:

CuSO4(s)+5H2O(l)→CuSO4.5H2O(s)+heat

Therfore in both A and B exothermic reactions are taking place resulting in rise in temperature. 

On the other hand in beaker C, an endothermic reaction is taking place as heat is being absorbed, resulting in a decrease in temperature.

NaCl+H2O+heat→Na++Cl−+H2O

Answer 2

Answer:

More Trees to Reduce Pollution’. You

may use the cues given below along with your own ideas.

• Increase of pollution

• Cutting down of trees

• Increase of respiratory diseases because of the lack of oxygen

• Benefits of trees