Q. The image of an object formed by a lens is of magnification-$1$ if the distance between the object and its image is $60$cm, what is the focal length of the lens? If the object is moved $20$cm towards the lens, where would the image be formed? State reason.

Q. On dropping a small piece of sodium in a test tube containing carbon compound ${}^{\prime }{X}^{\prime }$ with molecular formula $C_2{H}_{6}O$, a brisk effervescence is observed and a gas and $Y$ is produced. On bringing a burning splinter at the mouth of the test tube the gas evolved burns with a pop sound. Identify ${}^{\prime }{X}^{\prime }$ and ${}^{\prime }{Y}^{\prime }$. Also write the chemical equation for the reaction. Write the name and structure of the product formed, when you heat ${}^{\prime }{X}^{\prime }$ with excess conc. sulphuric acid?

Q. Write the Molecular formula of the compound when 'X' reacts with hydrogen and write its electron dot structure?

Q. Define focal length of a spherical lens.

Q. (a) Name the part marked. 'A' in the diagram.

Q. What are the organisms called which bear both the sex organs in the same individual. Give one example of such organism.

Q. Write one negative effect, on the environment, of affluent life style of few persons of a society.

Q. State the importance of green and blue dustbins in the safe disposal of the household waste.

Q. Forests are "biodiversity hot spots". Justify this statement.

Q. Describe an activity to show that the colours of white light splitted by a glass prism can be recombined to get white light by another identical glass prism.

Q. Why is it necessary to conserve our environment?

Q. List two values exhibited by your classmate who is an active member of Eco-club of your school.

Q. What is water harvesting? How can this technique help in the conservation of water?

Q. With the help of an example justify the following statement: "A trait may be inherited, but may not be expressed".

Q. How does 'A' reaches part 'B'?

Q. An aldehyde as well as a ketone can be represented by the same molecular formula, say $C_3{H}_{6}O$. Write their structures and name them. State the relation between the two in the language of science.

Q. Three elements 'X', 'Y' and 'Z' have atomic numbers $7,8,$ and $9$, respectively. Arrange these elements in the decreasing order of their atomic radii.

Q. Write the name and structure of an alcohol with four carbon atoms in its molecule.

Q. What happens to the part marked 'D' after the fertilisation?

Q. In the context of reproduction of species state the main difference between fission and fragmentation. Also, give one example of each.

Q. Explain the term "regeneration" as used in relation to reproduction of organisms. Describe briefly how regeneration is carried out in multicellular organisms like Hydra.

Q. "Two areas of study namely 'evolution' and 'classification' are interlinked". Justify this statement.

Q. Three elements 'X', 'Y' and 'Z' have atomic numbers $7,8,$ and $9$ respectively. State their positions (group number and period number both) in the modern periodic table.

Q. Three elements 'X', 'Y' and 'Z' have atomic numbers $7,8,$ and $9$ respectively. Write the formula of the compound formed when 'X' combines with 'Z'.

Q. A divergent lens has a focal length of $30$cm. At what distance should an object of height $5$cm from the optical centre of the lens be placed so that its image is formed $15$cm away from the lens? Find the size of the image also.

Q. State the importance of the part 'C'.

Q. An element $X$ belongs to $3^{rd}$ period and group $16$ of the Modern Periodic Table.
Determine the number of valence electrons and the valency of X?

Q. "The magnification produced by a spherical mirror is - $3$". List four informations you obtain from this statement about the mirror/image.

Q. List two reasons for the appearance of variations among the progeny formed by sexual reproduction.

Q. An element $X$ belongs to $3^{rd}$ period and group 16 of the Modern Periodic Table.
Name the element $X$ and state whether it is metallic or non-metallic.