[2 Mark Questions]

Question 12 Marks

In today's digital world, every human spends around a minimum eight hours with the digital electronic items which make their eyes to strain more and causes many eye problems. Still they undergo many exercises for their eyes during their working hours what would be your medical suggestion to reduce the stress and strain caused in the eyes?

Answer

In addition to the exercise for the strained eyes, my medical suggestion would be the usage of the anti-glare lens in their spectacles which reduces the impact of blue light emitted from digital items and artificial lighting. This would reduce the stress and strain caused. But still the exercise for eyes in repeated time interval should also be regularly followed.

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Question 22 Marks

Which of the following belong to the second trophic level?
i. Frog, butterfly, spider, rice weevil
ii. Parrot, frog, butterfly, spider.

Answer

The second trophic level is marked by the organisms which feed directly on the producers, thus, folowing organisms lie at the second tropic level.
i. Butterfly, rice weevil.
ii. Butterfly, parrot.

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Question 32 Marks

Alisha digs a pit in her garden and puts the following items in it.
• paper cups
• glass bowls
• fruit peels
• rubber slippers
She then covers the pit with soil. Which item will decompose first?

Answer

Fruit peels

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Question 42 Marks

A $6 \ cm$ tall object is placed perpendicular to the principal axis of a concave mirror of focal length $30 \ cm.$ The distance of the object from the mirror is $45 \ cm$. Use mirror formula to determine the position, nature and size of the image formed. Also draw labelled ray diagram to show the image formation in this case.

Answer

Given, Height of the object $= 6 \ cm$
Focal length$, f = - 30\ cm$
Object distance$, u = - 45\ cm$
Image distance$, v =$ ?
Height of image,$ h_i=$ ?
We have$, \frac{1}{f}=\frac{1}{v}+\frac{1}{u}$
$\frac{1}{-30}=\frac{1}{v}+\frac{1}{-45}$
$\frac{1}{-30}+\frac{1}{45}=\frac{1}{v}$
$\frac{1}{v}=\frac{-3+2}{90}$
$v=-90 \ cm$
Also, we have $m =\frac{h_i}{h_0}=\frac{-v}{u}$
$\frac{h_i}{6}=\frac{-(-90)}{-45}$
$\frac{h_i}{6}=-2$
$h_{i}=-12$

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Question 52 Marks

What is meant by circulation?

Answer

In order to transport the nutritive materials, waste materials, oxygen, carbon dioxide to the respective parts of the body, an extracellular fluid, blood circulates in our body. This process is called circulation.

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Question 62 Marks

What would be the consequence of a deficiency of haemoglobin in our body?

Answer

The deficiency of haemoglobin in the body is called anaemia. In anaemia, the blood is unable to carry the sufficient amount of oxygen required by the body. So, respiration would be less and less energy will be available to the body. A haemoglobin deficient person will feel weak, pale, lethargic and will be unable to perform heavy physical work.

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Question 72 Marks

Why are testes placed outside the abdominal cavity in the scrotal sac?

Answer

Testes are placed outside the body cavity in the scrotal sac because it requires a temperature 2°C lower than the normal body temperature for production of sperms.

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Question 82 Marks

What is a covalent bond? What type of bond exists in $(i) CCl_4 \ (ii) CaCl_2$?

Answer

The chemical bond formed $($between two atoms$)$ through the sharing of electrons is known as a covalent bond. The sharing of electrons between the two atoms takes place in such a way that both the atoms acquire stable electronic configurations of their nearest noble gas. The electron pairs shared by the two atoms are known as shared pairs.
$(i) CCl_4:$ The type of bond in carbon tetra chloride is covalent bond.
$(ii) CaCl_2:$ The type of bond in calcium chloride is ionic bond.

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Science [2 Mark Questions]

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