1.
Why is it not possible to see an atom with
naked eyes?
(Page No.34)
Answer:
The dimension of atoms is very small of the order of 1 nm. More than a million atoms when staked one over the other will make a layer that is barely as thick as a sheet of paper. Thus, we cannot see an atom with naked eyes.
Answer:
The dimension of atoms is very small of the order of 1 nm. More than a million atoms when staked one over the other will make a layer that is barely as thick as a sheet of paper. Thus, we cannot see an atom with naked eyes.
2.
Write down the formulae of (Page No.39)
(i) sodium oxide
(ii) aluminium chloride
(iii) sodium suphide
(iv) magnesium hydroxide
Answer:
(i) Na2O
(ii) AlCl3
(iii) Na2S
(iv) Mg(OH)2
(i) sodium oxide
(ii) aluminium chloride
(iii) sodium suphide
(iv) magnesium hydroxide
Answer:
(i) Na2O
(ii) AlCl3
(iii) Na2S
(iv) Mg(OH)2
3.
What
is immunization? (Page No.187)
Answer
Immunizationis defined as protection of the body from communicable diseases by administration
Answer
Immunizationis defined as protection of the body from communicable diseases by administration
of some agent that mimics the microbe.
4.
__________
virus is spread by the bite of infected
dog and ______animals.(Page No.187)
Answer: Rabies, others
5.
Define
1watt of Power?
Answer:
When one joule work is done in
one second by any agent, then its power is called to be one watt,
It is the unit
of Power.
6.
According
to the law of conservation of energy, energy can only be transformed from one
form to another, It neither __________ nor ____________,it always remains the
________.
Answer.
Created, destroyed, constant. (Page No.157)
7. Define Potential energy? (Page
No.153)
Answer: The energy stored in a
body or a system due to its position in a force field or due to its state
of
strain or configuration is called potential energy.
8.
State any
two conditions essential for being free of disease. (Page
No.178)
Answer
Two conditions essential for being disease-free are:
→ Person should take balance diet.
→ Personal and community hygiene.
Answer
Two conditions essential for being disease-free are:
→ Person should take balance diet.
→ Personal and community hygiene.