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Delhi: State Level Answer Key (SAT) - 2020-21

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 Page 1


 
  
 
NTSE STAGE – I (DELHI STATE) 
 (2020 – 21)  
 (For Class – X) 
SCHOLASTIC APTITUDE TEST 
ANSWER KEYS 
PHYSICS 
 101. 3 102. 1 103. 1 104. 2 
 105. 4 106. 4 107. 2 108. 4 
 109. 1 110. 2 111. 3 112. 1 
 113. 2 
CHEMISTRY 
 114. 2 115. 3 116. 3 117. 1 
 118. 1 119. 3 120. 4 121. 2 
 122. 2 123. 4 124. 4 125. 4 
 126. 1 
BIOLOGY 
 127. 3 128. 1 129. 2 130. 4 
 131. 4 132. 3 133. 2 134. 3 
 135. 3 136. 2 137. 2 138. 1 
 139. 1 140. 2 
 
MATHEMATICS 
 141. 3 142. 2 143. 2 144. 3 
 145. 3 146. 4 147. 4 148. 1 
 149. 1 150. 3 151. 4 152. 2 
 153. 2 154. 2 155. 2 156. 4 
 157. 3 158. 4 159. 3 160. 1 
 
SOCIAL SCIENCE 
 161. 1 162. 4 163. 2 164. 2 
 165. 3 166. 4 167. 3 168. 2 
 169. 1 170. 3 171. 4 172. 4 
 173. 1 174. 2 175. 2 176. 3 
177. 4 178. 2 179. 3 180. 2 
181. 2 182. 1 183. 4 184. 2 
185. 1 186. 3 187. 3 188. 3 
189. 3 190. 3 191. 4 192. 4 
193. 1 194. 1 195. 3 196. 4 
197. 2 198. 2 199. 2 200. 4 
Page 2


 
  
 
NTSE STAGE – I (DELHI STATE) 
 (2020 – 21)  
 (For Class – X) 
SCHOLASTIC APTITUDE TEST 
ANSWER KEYS 
PHYSICS 
 101. 3 102. 1 103. 1 104. 2 
 105. 4 106. 4 107. 2 108. 4 
 109. 1 110. 2 111. 3 112. 1 
 113. 2 
CHEMISTRY 
 114. 2 115. 3 116. 3 117. 1 
 118. 1 119. 3 120. 4 121. 2 
 122. 2 123. 4 124. 4 125. 4 
 126. 1 
BIOLOGY 
 127. 3 128. 1 129. 2 130. 4 
 131. 4 132. 3 133. 2 134. 3 
 135. 3 136. 2 137. 2 138. 1 
 139. 1 140. 2 
 
MATHEMATICS 
 141. 3 142. 2 143. 2 144. 3 
 145. 3 146. 4 147. 4 148. 1 
 149. 1 150. 3 151. 4 152. 2 
 153. 2 154. 2 155. 2 156. 4 
 157. 3 158. 4 159. 3 160. 1 
 
SOCIAL SCIENCE 
 161. 1 162. 4 163. 2 164. 2 
 165. 3 166. 4 167. 3 168. 2 
 169. 1 170. 3 171. 4 172. 4 
 173. 1 174. 2 175. 2 176. 3 
177. 4 178. 2 179. 3 180. 2 
181. 2 182. 1 183. 4 184. 2 
185. 1 186. 3 187. 3 188. 3 
189. 3 190. 3 191. 4 192. 4 
193. 1 194. 1 195. 3 196. 4 
197. 2 198. 2 199. 2 200. 4 
 
  
 
 
NTSE STAGE – I (DELHI STATE) 
 (2020 – 21)  
 (For Class – X) 
SCHOLASTIC APTITUDE TEST 
 
HINTS & SOLUTIONS 
 
PHYSICS 
 
101. 3 
101. Quality of sound helps to distinguish between two sounds. 
 
102. 1 
102. Power (p) = 
W mgh 30 9.8 10
t t 60
? ?
? ? = 49 J/s 
 
103. 1 
103. R
AB
 = 
5R
11
 
 R
BC
 = 
3R
11
 
 R
AC
 = 
4R
11
 
 
104. 2 
104. F = kx = 15 × 0.2 = 3 N 
 
F 3
a
m 0.3
? ? = 10 m/s
2
 
 
105. 4 
105. As slope of v–t graph is decreasing between points A and B. So acceleration is decreasing.  
 
106. 4 
106. A retarding force of any magnitude can stop the moving body. 
 
107. 2 
107. As, W = VQ 
 ? 
18
Q
90
? = 0.2 C 
 
108. 4 
108. Magnetic filed lines are closed curve because magnetic monopoles do not exist.  
 
109. 1 
109. Average speed = 
1 2
S
S 4S
5V 5V
?
 
 ? 
1 2
2 1
5V V
V 4V ?
     
 
Page 3


 
  
 
NTSE STAGE – I (DELHI STATE) 
 (2020 – 21)  
 (For Class – X) 
SCHOLASTIC APTITUDE TEST 
ANSWER KEYS 
PHYSICS 
 101. 3 102. 1 103. 1 104. 2 
 105. 4 106. 4 107. 2 108. 4 
 109. 1 110. 2 111. 3 112. 1 
 113. 2 
CHEMISTRY 
 114. 2 115. 3 116. 3 117. 1 
 118. 1 119. 3 120. 4 121. 2 
 122. 2 123. 4 124. 4 125. 4 
 126. 1 
BIOLOGY 
 127. 3 128. 1 129. 2 130. 4 
 131. 4 132. 3 133. 2 134. 3 
 135. 3 136. 2 137. 2 138. 1 
 139. 1 140. 2 
 
MATHEMATICS 
 141. 3 142. 2 143. 2 144. 3 
 145. 3 146. 4 147. 4 148. 1 
 149. 1 150. 3 151. 4 152. 2 
 153. 2 154. 2 155. 2 156. 4 
 157. 3 158. 4 159. 3 160. 1 
 
SOCIAL SCIENCE 
 161. 1 162. 4 163. 2 164. 2 
 165. 3 166. 4 167. 3 168. 2 
 169. 1 170. 3 171. 4 172. 4 
 173. 1 174. 2 175. 2 176. 3 
177. 4 178. 2 179. 3 180. 2 
181. 2 182. 1 183. 4 184. 2 
185. 1 186. 3 187. 3 188. 3 
189. 3 190. 3 191. 4 192. 4 
193. 1 194. 1 195. 3 196. 4 
197. 2 198. 2 199. 2 200. 4 
 
  
 
 
NTSE STAGE – I (DELHI STATE) 
 (2020 – 21)  
 (For Class – X) 
SCHOLASTIC APTITUDE TEST 
 
HINTS & SOLUTIONS 
 
PHYSICS 
 
101. 3 
101. Quality of sound helps to distinguish between two sounds. 
 
102. 1 
102. Power (p) = 
W mgh 30 9.8 10
t t 60
? ?
? ? = 49 J/s 
 
103. 1 
103. R
AB
 = 
5R
11
 
 R
BC
 = 
3R
11
 
 R
AC
 = 
4R
11
 
 
104. 2 
104. F = kx = 15 × 0.2 = 3 N 
 
F 3
a
m 0.3
? ? = 10 m/s
2
 
 
105. 4 
105. As slope of v–t graph is decreasing between points A and B. So acceleration is decreasing.  
 
106. 4 
106. A retarding force of any magnitude can stop the moving body. 
 
107. 2 
107. As, W = VQ 
 ? 
18
Q
90
? = 0.2 C 
 
108. 4 
108. Magnetic filed lines are closed curve because magnetic monopoles do not exist.  
 
109. 1 
109. Average speed = 
1 2
S
S 4S
5V 5V
?
 
 ? 
1 2
2 1
5V V
V 4V ?
     
 
 
  
 
110. 2 
110. Refractive index = 
C
V
 
 
C
n
V
?    ?   
C
V
n
? 
 Distance = speed × time 
 
C
t (time)
n
? 
 Time  ?  
nt
C
 
 
111. 3 
111. 
eq
20
R
3
? ?   ;     
max
2.2
I
20
3
?
? ?
? ?
? ?
       ?    0.33 A 
 
eq
20 110
R 30
3 3
? ? ? ?  
 
min
2.2
I
110
3
?
? ?
? ?
? ?
   ;   I
min 
= 0.06 A 
 
112. 1 
112. 
2
A
V u 2gh ? ? 
 
2
B
V u 2gh ? ? 
 For C: Vertical velocity 
y
V 2gh ? 
  Horizontal velocity = u 
  
2 2
C x y
V V V ? ? 
 ? 
2
u 2gh ? 
  V
A
 = V
B
 = V
C
  
 
113. 2 
113. u = –12 
 
v 5
m
u 2
? ?
? ? 
 ?    
V 5
12 2
? ?
?
?
 
 V = –30 cm 
 
1 1 1
v u f
? ?   ;   
1 1 1
30 12 f
? ?
? ?
    
 ?    f = –8.6 cm 
 
CHEMISTRY 
114. 2 
114. ? ? ? ? ? ?
3 2 2
2
2Pb NO 2PbO 4NO O
?
?? ? ? ? ? ? 
Page 4


 
  
 
NTSE STAGE – I (DELHI STATE) 
 (2020 – 21)  
 (For Class – X) 
SCHOLASTIC APTITUDE TEST 
ANSWER KEYS 
PHYSICS 
 101. 3 102. 1 103. 1 104. 2 
 105. 4 106. 4 107. 2 108. 4 
 109. 1 110. 2 111. 3 112. 1 
 113. 2 
CHEMISTRY 
 114. 2 115. 3 116. 3 117. 1 
 118. 1 119. 3 120. 4 121. 2 
 122. 2 123. 4 124. 4 125. 4 
 126. 1 
BIOLOGY 
 127. 3 128. 1 129. 2 130. 4 
 131. 4 132. 3 133. 2 134. 3 
 135. 3 136. 2 137. 2 138. 1 
 139. 1 140. 2 
 
MATHEMATICS 
 141. 3 142. 2 143. 2 144. 3 
 145. 3 146. 4 147. 4 148. 1 
 149. 1 150. 3 151. 4 152. 2 
 153. 2 154. 2 155. 2 156. 4 
 157. 3 158. 4 159. 3 160. 1 
 
SOCIAL SCIENCE 
 161. 1 162. 4 163. 2 164. 2 
 165. 3 166. 4 167. 3 168. 2 
 169. 1 170. 3 171. 4 172. 4 
 173. 1 174. 2 175. 2 176. 3 
177. 4 178. 2 179. 3 180. 2 
181. 2 182. 1 183. 4 184. 2 
185. 1 186. 3 187. 3 188. 3 
189. 3 190. 3 191. 4 192. 4 
193. 1 194. 1 195. 3 196. 4 
197. 2 198. 2 199. 2 200. 4 
 
  
 
 
NTSE STAGE – I (DELHI STATE) 
 (2020 – 21)  
 (For Class – X) 
SCHOLASTIC APTITUDE TEST 
 
HINTS & SOLUTIONS 
 
PHYSICS 
 
101. 3 
101. Quality of sound helps to distinguish between two sounds. 
 
102. 1 
102. Power (p) = 
W mgh 30 9.8 10
t t 60
? ?
? ? = 49 J/s 
 
103. 1 
103. R
AB
 = 
5R
11
 
 R
BC
 = 
3R
11
 
 R
AC
 = 
4R
11
 
 
104. 2 
104. F = kx = 15 × 0.2 = 3 N 
 
F 3
a
m 0.3
? ? = 10 m/s
2
 
 
105. 4 
105. As slope of v–t graph is decreasing between points A and B. So acceleration is decreasing.  
 
106. 4 
106. A retarding force of any magnitude can stop the moving body. 
 
107. 2 
107. As, W = VQ 
 ? 
18
Q
90
? = 0.2 C 
 
108. 4 
108. Magnetic filed lines are closed curve because magnetic monopoles do not exist.  
 
109. 1 
109. Average speed = 
1 2
S
S 4S
5V 5V
?
 
 ? 
1 2
2 1
5V V
V 4V ?
     
 
 
  
 
110. 2 
110. Refractive index = 
C
V
 
 
C
n
V
?    ?   
C
V
n
? 
 Distance = speed × time 
 
C
t (time)
n
? 
 Time  ?  
nt
C
 
 
111. 3 
111. 
eq
20
R
3
? ?   ;     
max
2.2
I
20
3
?
? ?
? ?
? ?
       ?    0.33 A 
 
eq
20 110
R 30
3 3
? ? ? ?  
 
min
2.2
I
110
3
?
? ?
? ?
? ?
   ;   I
min 
= 0.06 A 
 
112. 1 
112. 
2
A
V u 2gh ? ? 
 
2
B
V u 2gh ? ? 
 For C: Vertical velocity 
y
V 2gh ? 
  Horizontal velocity = u 
  
2 2
C x y
V V V ? ? 
 ? 
2
u 2gh ? 
  V
A
 = V
B
 = V
C
  
 
113. 2 
113. u = –12 
 
v 5
m
u 2
? ?
? ? 
 ?    
V 5
12 2
? ?
?
?
 
 V = –30 cm 
 
1 1 1
v u f
? ?   ;   
1 1 1
30 12 f
? ?
? ?
    
 ?    f = –8.6 cm 
 
CHEMISTRY 
114. 2 
114. ? ? ? ? ? ?
3 2 2
2
2Pb NO 2PbO 4NO O
?
?? ? ? ? ? ? 
 
  
 
 
115. 3 
115. ? ? ? ?
3 2 3
2
Yellow ppt.
Pb NO 2KI PbI 2KNO ? ?? ? ? ? 
 
116. 3 
116. NaHCO
3
 + Tartaric acid 
 
117. 1 
117. 3 mole conc. HCl + 1 mole conc. HNO
3
 
 
118. 1 
118. 
2 4
Conc.H SO
3 2 2 2 2
443K
CH CH OH H C CH (Ethene) H O ?? ??? ? ? ? ? 
 
119. 3 
119. Denatured alcohol is a mixture of C
2
H
5
OH and CH
3
OH. 
 
120. 4 
120. For welding a mixture of oxygen and ethyne is burnt. 
 
121. 2 
121. Si < Be < Al < K 
 
122. 2 
122. CuO is insoluble in water. 
 
123. 4 
123. KO
2
 turns red litmus into blue. 
 
124. 4 
124. SO
2
 is not a green house gas. 
 
125. 4 
125. Aluminium does not show allotropy. 
 
126. 1 
126. (1) 100 g of He 
A
100
25N
4
? ? 
 (2) 100 g of Na = 4.3 N
A
 
 (3) 100 g of Li = 14.28 N
A
 
 (4) 100 g of Al = 3.70 N
A 
  
 
BIOLOGY 
127. 3 
127. ? Absorption of light energy by chlorophyll. 
 ? Breakdown of H
2
O into Hydrogen and Oxygen and Conversion of light energy into 
chemical energy 
 ? Reduction of carbon dioxide to carbohydrates. 
 
Page 5


 
  
 
NTSE STAGE – I (DELHI STATE) 
 (2020 – 21)  
 (For Class – X) 
SCHOLASTIC APTITUDE TEST 
ANSWER KEYS 
PHYSICS 
 101. 3 102. 1 103. 1 104. 2 
 105. 4 106. 4 107. 2 108. 4 
 109. 1 110. 2 111. 3 112. 1 
 113. 2 
CHEMISTRY 
 114. 2 115. 3 116. 3 117. 1 
 118. 1 119. 3 120. 4 121. 2 
 122. 2 123. 4 124. 4 125. 4 
 126. 1 
BIOLOGY 
 127. 3 128. 1 129. 2 130. 4 
 131. 4 132. 3 133. 2 134. 3 
 135. 3 136. 2 137. 2 138. 1 
 139. 1 140. 2 
 
MATHEMATICS 
 141. 3 142. 2 143. 2 144. 3 
 145. 3 146. 4 147. 4 148. 1 
 149. 1 150. 3 151. 4 152. 2 
 153. 2 154. 2 155. 2 156. 4 
 157. 3 158. 4 159. 3 160. 1 
 
SOCIAL SCIENCE 
 161. 1 162. 4 163. 2 164. 2 
 165. 3 166. 4 167. 3 168. 2 
 169. 1 170. 3 171. 4 172. 4 
 173. 1 174. 2 175. 2 176. 3 
177. 4 178. 2 179. 3 180. 2 
181. 2 182. 1 183. 4 184. 2 
185. 1 186. 3 187. 3 188. 3 
189. 3 190. 3 191. 4 192. 4 
193. 1 194. 1 195. 3 196. 4 
197. 2 198. 2 199. 2 200. 4 
 
  
 
 
NTSE STAGE – I (DELHI STATE) 
 (2020 – 21)  
 (For Class – X) 
SCHOLASTIC APTITUDE TEST 
 
HINTS & SOLUTIONS 
 
PHYSICS 
 
101. 3 
101. Quality of sound helps to distinguish between two sounds. 
 
102. 1 
102. Power (p) = 
W mgh 30 9.8 10
t t 60
? ?
? ? = 49 J/s 
 
103. 1 
103. R
AB
 = 
5R
11
 
 R
BC
 = 
3R
11
 
 R
AC
 = 
4R
11
 
 
104. 2 
104. F = kx = 15 × 0.2 = 3 N 
 
F 3
a
m 0.3
? ? = 10 m/s
2
 
 
105. 4 
105. As slope of v–t graph is decreasing between points A and B. So acceleration is decreasing.  
 
106. 4 
106. A retarding force of any magnitude can stop the moving body. 
 
107. 2 
107. As, W = VQ 
 ? 
18
Q
90
? = 0.2 C 
 
108. 4 
108. Magnetic filed lines are closed curve because magnetic monopoles do not exist.  
 
109. 1 
109. Average speed = 
1 2
S
S 4S
5V 5V
?
 
 ? 
1 2
2 1
5V V
V 4V ?
     
 
 
  
 
110. 2 
110. Refractive index = 
C
V
 
 
C
n
V
?    ?   
C
V
n
? 
 Distance = speed × time 
 
C
t (time)
n
? 
 Time  ?  
nt
C
 
 
111. 3 
111. 
eq
20
R
3
? ?   ;     
max
2.2
I
20
3
?
? ?
? ?
? ?
       ?    0.33 A 
 
eq
20 110
R 30
3 3
? ? ? ?  
 
min
2.2
I
110
3
?
? ?
? ?
? ?
   ;   I
min 
= 0.06 A 
 
112. 1 
112. 
2
A
V u 2gh ? ? 
 
2
B
V u 2gh ? ? 
 For C: Vertical velocity 
y
V 2gh ? 
  Horizontal velocity = u 
  
2 2
C x y
V V V ? ? 
 ? 
2
u 2gh ? 
  V
A
 = V
B
 = V
C
  
 
113. 2 
113. u = –12 
 
v 5
m
u 2
? ?
? ? 
 ?    
V 5
12 2
? ?
?
?
 
 V = –30 cm 
 
1 1 1
v u f
? ?   ;   
1 1 1
30 12 f
? ?
? ?
    
 ?    f = –8.6 cm 
 
CHEMISTRY 
114. 2 
114. ? ? ? ? ? ?
3 2 2
2
2Pb NO 2PbO 4NO O
?
?? ? ? ? ? ? 
 
  
 
 
115. 3 
115. ? ? ? ?
3 2 3
2
Yellow ppt.
Pb NO 2KI PbI 2KNO ? ?? ? ? ? 
 
116. 3 
116. NaHCO
3
 + Tartaric acid 
 
117. 1 
117. 3 mole conc. HCl + 1 mole conc. HNO
3
 
 
118. 1 
118. 
2 4
Conc.H SO
3 2 2 2 2
443K
CH CH OH H C CH (Ethene) H O ?? ??? ? ? ? ? 
 
119. 3 
119. Denatured alcohol is a mixture of C
2
H
5
OH and CH
3
OH. 
 
120. 4 
120. For welding a mixture of oxygen and ethyne is burnt. 
 
121. 2 
121. Si < Be < Al < K 
 
122. 2 
122. CuO is insoluble in water. 
 
123. 4 
123. KO
2
 turns red litmus into blue. 
 
124. 4 
124. SO
2
 is not a green house gas. 
 
125. 4 
125. Aluminium does not show allotropy. 
 
126. 1 
126. (1) 100 g of He 
A
100
25N
4
? ? 
 (2) 100 g of Na = 4.3 N
A
 
 (3) 100 g of Li = 14.28 N
A
 
 (4) 100 g of Al = 3.70 N
A 
  
 
BIOLOGY 
127. 3 
127. ? Absorption of light energy by chlorophyll. 
 ? Breakdown of H
2
O into Hydrogen and Oxygen and Conversion of light energy into 
chemical energy 
 ? Reduction of carbon dioxide to carbohydrates. 
 
 
  
 
128. 1 
128.  Lion 
Grass 
Insects
 
Deer 
Monkey
 
 
 
129. 2 
129. In stratosphere the ozone is formed naturally through the interaction of solar ultraviolet 
radiation with molecular O
2
. 
 
130. 4 
130.  
Column-I  Column-II 
(i) Regeneration (d) Planaria 
(ii) Rhizophus (e) Spores 
(iii) Plumule (a) Shoot 
(iv) Rose (c) Vegetative Propagation 
(v) Stigma (b) Pollen grain 
   
131. 4 
131. The opening and closing of stomata regulated by water in guard cells. 
 
132. 3 
132. Total = 2432 seeds 
 
2432
152
16
? 
 Dihybrid cross ratio = 9 : 3 : 3 : 1 
  152 ? 9 = 1368 
 
 Yellow round  – 9 
 Yellow wrinkled  – 3 
 Green round  – 3 
 Green wrinkled  – 1 
 
133. 2 
133. The stakeholders of various forest products are: 
 ? People living near forests  
 ? Government only 
 ? Nature lovers 
 
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