How many times in one second does an $AC$ with frequency $50 Hz$ change its direction?
- A$25$
- B$50$
- ✓$100$
- D$200$
Answer: C.
View full solution →209 questions across 8 question groups — pick any mix to generate a Science paper with step-by-step answer keys.
M.C.Q
22 Q→02Fill in the blank
18 Q→03True-False
17 Q→04[1 Mark Questions]
72 Q→05[2 Mark Questions]
38 Q→06[3 Mark Questions]
11 Q→07[4 marks Questions]
26 Q→08MATCH THE FOLLOWING.
5 Q→One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
Answer: C.
View full solution →Answer: B.
View full solution →Answer: A.
View full solution →Answer: B.
View full solution →Answer: A.
View full solution →| $(a)$ | Bio-magnification | Accumulation of chemicals at each stage of the food chain |
| $(b)$ | Ecosystem | Biotic components of the environment |
| $(c)$ | Aquarium | Man-made ecosystem |
| $(d)$ | Parasite | An organism that obtains nutrition from other organisms |
| $'A'$ | $'B'$ | |
| $Q.1$. Biotic components | $(a)$ | temperature |
| $Q.2$. Abiotic Component | $(b)$ | Bacteria |
| $(c)$ | Paper | |
| 'A' | 'B' | |
| $Q.1$. Ozone | $(a)$ | Water pollution |
| $Q.2$. Accumulation of pesticides in the water | $(b)$ | Biological magnification |
| $(c)$ | A deadly poison | |
| 'A' | 'B' | |
| $Q.1$. Accumulation of non degradable substances in human | $(a)$ | Water pollution |
| $Q.2$. Ultraviolet radiations | $(b)$ | Biological magnification |
| $(c)$ | Skin cancer | |
| 'A' | 'B' | |
| $Q.1$. Sulphur bacteria | $(a)$ | Autotrophic nutrition |
| $Q.2$. Snake | $(b)$ | Nondegradable waste |
| $(c)$ | Consumers | |
| 'A' | 'B' | |
| $Q.1$. Polythene | $(a)$ | Biodegradable waste |
| $Q.2$. Dry wood | $(b)$ | Nondegradable waste |
| $(c)$ | Autotrophic nutrition | |
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