CTET Solved Paper - UPTET December 2016 Paper2
121. The Oxidation state of iron in Fe(CO)3 is
- Option : A
- Explanation : (A) The oxidation number of iron in Fe(CO)3 is
Oxidation state of Fe = x (let)
∴ x + 5 × 0 = 0
Because CO is neutral molecule.
122. Compound responsible for temporary hardness of water is
- Option : A
- Explanation : (A) Temporary hardness of water is because of the presence of bicarbonate of calcium and magnesium. It can be easily removed by just boiling and filtering the water.
is
- Option : C
- Explanation : (C)
∠DAC = 320 and ∠AOB = 700 (given)
∠BOC + ∠AOB = 1800 [∵ Liner pair]
⇒ ∠BOC + 700 = 1800
⇒ ∠BOC = 1800 - 700 = 1100
∠ACB = ∠DAC [∵ Alternate angles between the parallel lines]
⇒ ∠ACB = 320 [∵ ∠DAC = 320 (given)]
or ∠OCB = 320
Now, in △OCB, ∠OCB + ∠BOC + ∠OBC = 1800 [∵ Angle sum property of a triangle]
⇒ 320 + 1100 + ∠OBC = 1800
⇒ ∠OBC = 1800 - (1100 + 320)
⇒ ∠OBC = 380 = x
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