# Chemistry (2017) | Study Mode

Question 21
A

226

B

220

C

227

D

222

##### Explanation

$$^{226}_{88}Ra$$ $$^x_{86}Rn$$ + $$^4_{2}He$$

$$^4_{2}He$$ = alpha particle

considering the summation of the mass number

226 = x + 4

x = 226 + 4

x = 222

Question 22
A
trigonal planar
B
octahedral
C
square planar
D
tetrahedral
##### Explanation
Ammonia = NH3

It has three bonds of hydrogen to the Nitrogen.

Question 23
A
54.0g
B
27.0g
C
13.5g
D
108.0g
##### Explanation
Recall that

m = $$\frac{MmIt}{96500n}$$

Mm =108, t = 4830s

I = 10A, n = 1

m = 108 x 10 x ($$\frac{4830}{96500}$$) x 1

m = 54.0g

Mass deposited = Mm x $$\frac{It}{96500n}$$

Question 24
A
Low melting point
B
Weak electropositive character
C
High boiling point
D
White lustrous appearance
##### Explanation
Tin has a melting point of 232 which enables it to be unaffected by air at ordinary temperature coupled with the fact that it also helps in making a good metal for alloying.

Tin is relatively unaffected by both water and oxygen at room temperature due to its low melting point. It does not rust, corrode, or react in any other way. This explains one of its major uses: as a coating to protect other metals.

Question 25
A
0.05
B
10.8
C
10
D
0.1
##### Explanation
m = $$\frac{Mm \times Q}{96500n }$$

where Q = IT

M = Mm x $$\frac{Q}{96500n}$$

where m = mass

Mm = Molar mass

Q = Quantity of electricity

n = number of change= +1

$$\frac{M}{Mm}$$ = mole = $$\frac{mass}{Molarmass}$$

$$\frac{M}{Mm}$$ = $$\frac{Q}{96500n}$$

= $$\frac{9650}{96500n}$$ x 1

= $$\frac{1}{10}$$ = 0.1mol

Question 26
A
oxidation reaction
B
C
hydrogenation reaction
D
substitution reaction
##### Explanation
Alkanes undergoes substitution reaction and it is an example of halogenation substitution reaction.

Reaction of halogen with alkane in the presence of sunlight (ultraviolet) is termed halogenation. Halogenation is an example of substitution reaction. In addition, alkanes only undergo substitution reaction but not addition reaction.

Question 27
A
amylase
B
diastatse
C
invertase
D
zymase
##### Explanation
This is any amylase or a mixture of amylases that converts starch to dextrin and maltose.

Question 28
A

CnH2n

B

CnH2n - 2

C

CnH2n + 1

D

CnH2n + 2

##### Explanation

Alkyl group has the general formula CnH2n + 1.

This formed when one hydrogen is removed from the alkane family. It has the general formula CnH2n + 1

Question 29
A
0 to + 2
B
0 to + 1
C
C + 1 to 0
D
+ 2 to + 1
##### Explanation
In the reactant;

Cu2S

2 Cu - 2(1) = 0

2 Cu = 2

Cu = $$\frac{2}{2}$$

Cu = +1

In the product, Cu

Cu = O

The oxidation number of Cu in Cu2S and Cu respectively is +1 and 0 respectively

Question 30
A

SO3

B

SO2

C

S

D

H2S

##### Explanation
The setup represents the production of sulfur dioxide. And the cylinder marked X is SO2

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