Chemistry MCQ
Which of the following both acts as an oxidizing and a reducing agent?
HNO3
SO2
H2SO4
H2S
12. Water soluble bases are alkalis.
False
True
13. Which electrode is used in pH meter?
cathode
anode
Combined Glass Electrode
Platinum electrode
14. pH range of Phenolphthalein indicator is
8.3 - 10.0
3.1 - 5.5
5.5 - 7.5
4.2 - 6.8
15. pH range of Methyl Orange indicator is
3.1 - 4.4
5.3 - 7.6
8.3 - 10.0
4.2 - 6.3
16. The volume of 0.25N HCl required to neutralise 25 ml of 0.75N NaOH solution is
25 ml
8.33 ml
7.5 ml
75 ml
17. 1000 ml of a solution containing 6.3 gms. of Oxalic acid (H2C2O4.2H2O) is
Formal Solution
Deci-normal solution
Normal Solution
Molar Solution
18. What is the pH value of Human Blood?
7.2
6.85
7.35- 7.45
6.5- 8.5
19. What should be the nature of NH4Cl solution?
Neutral
Alkaline
Acidic
None of the above
20. pH depends on
Pressure
Temperature
None of the above
Answers
Answers:
11) Sulphur Dioxide acts as both an oxidizing as well as a reducing agent.
Examples:
=>SO2 gas oxidizes H2S gas to give yellow sulphur particles.
=> SO2 gas reduces Mn7+ in KMnO4 to Mn2+ in MnO2 .
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12) True, Water soluble bases are called alkalis.
Examples: NaOH , KOH, LiOH.
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13) Combined Glass Electrodes are used in making PH meters.
Explanation: Combined glass electrodes are specially designed electrodes that are sensitive to certain ions, such as H+ in the pH meter.
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14) pH Range of Phenolphthalein indicator is 8.3-10.0 .
Explanation: Phenolphthalein indicator turns pink between pH 8.3-10.0 .
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15) pH range of Methyl Orange Indicator is 3.1-4.4 .
Explanation: Methyl Orange indicator turns red between pH 3.1-4.4 .
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16) 75 mL of 0.25 N HCl solution is needed.
Explanation:
HCl + NaOH ---------------> NaCl + H2O
⏩1 part of HCl reacts with 1 part of NaOH.
⏩ 25 mL or 0.025 L of 0.75 N NaOH is to be neutralized.
⏩ Acidity of NaOH = 1 (Monoacidic)
⏩ Normality = Molarity x Acidity =>0.75 = 1 x Molarity =>Molarity =0.75 M
⏩Molarity = (moles of solute)/Liters of solution
=> 0.75 = moles/0.025
=> moles of NaOH = 0.75 x 0.025 => 0.01875 moles of NaOH.
⏩ 1 part of NaOH = 0.01875 moles of NaOH.
⏩ 1 part of HCl = 1 x 0.01875 moles => 0.01875 moles of HCl.
⏩ Normality of HCl solution = 0.25 N
⏩ Basicity of HCl = 1
⏩ Normality = Basicity x Molarity=>0.25=1 x Molarity=>Molarity = 0.25 M
⏩ Molarity = (moles of HCl) / (litres of solution)
⏩ 0.25 = 0.01875 / liters of solution =>volume=0.01875/0.25=>0.075 L
Hence, 0.075 x 1000 mL =>75 mL of HCl solution is required.
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17) The solution is Deci-normal in nature(0.1 N Normality).
Explanation:
⏩ Volume of solution = 1 L
⏩ Mass of solute ( H2C2O4.2H2O) = 6.3 grams
⏩ Molar mass of Oxalic acid is 2+24+64+36 => 126 grams per mole.
⏩ So, 6.3 grams is 6.3/126 moles =>1/20 =>0.05 moles of Oxalic acid.
⏩ Molarity = (moles of oxalic acid)/(liters of solution) =>0.05/1 => 0.05 M
⏩ Basicity of Oxalic acid is 2. ( 2H+ ions per molecule in aqueous state)
⏩ Normality = molarity x basicity => 0.05 x 2 => 0.1 N .
⏩ A 1 N solution is a normal solution, 0.1 N solution is Decinormal.
⏩ So, the oxalic acid solution is 0.1 N or Decinormal.
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18) The pH value of blood is 7.35 - 7.45 .
Explanation: Blood is slightly alkaline in nature as it contains HCO3-1 or Bicarbonate ions dissolved in blood plasma.
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19) NH4Cl solution is acidic in nature.
Explanation: NH4Cl is formed when a weak alkali (NH4OH) reacts with a strong acid HCl, so it is acidic in nature.
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20) pH depends on Temperature.
Explanation: pH decreases slightly with increase in temperature.