Question
Write the two causes of human population explosion. Explain with the help of suitable examples how this explosion can be checked.
✓
Answer
The two causes of population explosion are:
- Decline in death rate (including maternal mortality rate and infant mortality rate).
- Increase in the number of people in the reproducible age.
- One-child norm.
- Increasing the marriageable age.
- Promoting contraceptive methods.
- Natural means of contraception.
- Artificial means of contraception.
- Avoiding the coming together of ovum and sperm.
- Periodic abstinence: Avoiding coitus from days 10 to 17 of the menstrual cycle.
- Coitus interrupts: Withdrawal of penis before ejaculation.
- Lactational amenorrhea: It is the absence of menstruation during lactation. So, in the lactation period, the chances of conception are almost zero.
- Physically preventing the coming together of ovum and sperm.
- Barriers: Include condoms, diaphragms, cervical caps and vaults.
- Intra uterine devices (IUDs): They release hormones to cause phagocytosis of sperms, or they release copper ions to decrease sperm motility.
- Oral contraceptive pills: They contain hormones-either progesterone or progesterone-oestrogen combination.
- Surgical methods: Include vasectomy (removal of a part of the vas deferens in males) and tubectomy (removal of a part of the fallopian tubes in females).
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$\text{H}\ \ \ \ \ \ \ \text{Li} \ \ \ \ \ \ \ \text{Be} \ \ \ \ \ \ \ \ \ \text{B}\ \ \ \ \ \ \ \text{C}\ \ \ \ \ \ \ \text{N}\ \ \ \ \ \ \ \text{O}\\\text{F}\ \ \ \ \ \ \ \text{Na}\ \ \ \ \ \ \text{Mg}\ \ \ \ \ \ \ \text{Al}\ \ \ \ \ \ \text{Si}\ \ \ \ \ \ \ \text{P}\ \ \ \ \ \ \ \ \text{S}$
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Which law of classification of element is illustrated by the above arrangement of elements?
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State one limitation of this classification of elements.
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|
Group
→
Period
↓
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1
|
2
|
3 to 12
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13
|
14
|
15
|
16
|
17
|
18
|
|
1
|
G
|
|
|
|
|
|
|
|
H
|
|
2
|
A
|
|
|
I
|
|
|
B
|
|
C
|
|
3
|
|
D
|
|
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E
|
|
|
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F
|
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