Solution

CₙH₂ₙ₊₂: Alkane series Name: Ethane (2nd member) Formula: C₂H₆

Solution

Because the image size is equal to the size of the object, the magnification of the image created by a plane mirror is 1.

Solution

The degree of convergence or divergence of light rays falling on a lens is measured by its power. A lens's power is equal to the reciprocal of its focal length in metres.

Solution

Multiple fission
Many daughter cells are formed from the splitting of the parent’s cell or Nucleus.
Occurs during unfavourable conditions.
Divides repeatedly.
First, the nucleus divides and is surrounded by cytoplasm.
Has no definite pattern of division.
Example: Plasmodium, Sporozoans, Algae, etc.

Binary fission
2 daughter cells are formed from the splitting of the parent’s cell or Nucleus.
Occurs during favourable conditions.
Divides only once.
Both the Nucleus and cytoplasm divide simultaneously.
Includes a definite pattern of division.
Example: Amoeba, Bacteria, Euglena, etc.,

Solution

(a) We need to manage our natural resources because of the following reasons:
The resources of the earth are limited. As the human population is increasing rapidly, the demand for resources increases day by day. The proper management can ensure that these resources last for the generations to come.
(b) The proper management of natural resources takes into consideration a long-term perspective so that these natural resources are used judiciously at present and their exploitation to the hilt for short term gains is prevented. This is essential to meet their future needs and demands.

Solution

Forests can be conserved in the following ways:

By silviculture—It means reforesting those forest lands from where large number of trees have been cut in a planned way.
By taking the help of the local people in conserving the forests, e.g., Sal forests of Arabari forest range of West Bengal were conserved with the help of the local people by the Forest Department of that state.
Encouraging the people not to overuse the materials obtained from the forests, e.g., timber.
Indiscriminate felling of trees for commercial gains should be stopped.
Overgrazing in forests should be discouraged and forest fires should be prevented.

Solution

Valence Electrons Na: 1, Mg: 2, Al: 3
i. Because the size of the atom shrinks as one moves from left to right in the periodic table, Na has the biggest atomic radius. This is due to an increase in positive charge on the nucleus, which pushes the outermost electrons in closer to the nucleus, reducing the size of the atom.
ii. Because the nuclear charge increases as you move from left to right in the periodic table, the valence electrons are drawn in closer to the nucleus, making Al the least reactive element.

Solution

Solution

The organic compounds having the same molecular formula but different structures are known as isomers.
Isomers of C4H10:
<p><img src="" alt="C4H10">
Isomers of first three members, i.e., methane, ethane and propane are not possible because they are too short and cannot be branched.<p>

Solution

Sexually transmitted diseases, or STDs, are infections that are passed from an infected person to a healthy person through sexual contact.
STDs can be caused by a variety of factors, including:
i. Gonorrhoea and Syphilis are bacterial infections; AIDS and Herpes are viral infections.
ii. Condoms can help prevent the transmission of certain infections.