Q. The minimum distance between the source of sound and the reflecting surface necessary to cause echo is

1. $1.7m$
2. $17m$
3. $7m$
4. $70m$

Q. 'Soda glass must not be used in making laboratory heating apparatus.' Justify.

Q. Explain the method of extraction of amorphous silicon with the help of chemical equation.

Q. How are feathers useful to birds?

Q. In a triad of $A,B,C$ elements, if the atomic masses of $A$ and $C$ respectively are $100$ and $200$, then the atomic mass of $B$ is:

1. $175$
2. $300$
3. $125$
4. $150$

Q. Write the function of the following parts of nuclear reactor along with material used in making it.
a. Control rod
b. Moderator

Q. What are functional groups? Name the class of compounds containing $-N{H}_2$ as the functional group.

Q. Which one of the following is a biodegradable pollutants?

1. Cowdung
2. DDT
3. Lead Vapour
4. Plastic

Q. Select the correct group among the following.

1. Disease - syphilis, pathogen - Neisseria, symptoms - ulcers on nose
2. Disease - herpes, pathogen - HSV, symptoms - blisters on and around genitals
3. Disease - gonorrhea, pathogen - Treponema, symptoms - vaginal discharge
4. Disease - hepatitis - B, pathogen - HCV, symptoms - liver cirrhosis

Q. The major constituent of freshly obtained molasses is:

1. sucrose
2. fructose
3. glucose
4. methanol

Q. Names of alloys are given in List - A. Match them with their constituents given in List - B and uses given in the List - C.

List - A	List - B	List - C
A. Stainless Steel	a. Iron + nickel + cobalt + aluminium	i. Electrical contact part
B. Alnico	b. Iron + carbon + chrominum + nickel	ii. Sports medal
C. Invar Steel	c. Copper + zinc + tin	iii. Surgical instruments
D. Brass	d. Iron + carbon + nickel (large quantity)	iv. Aeroplane body
	e. Aluminium + copper + magnesium + manganese	v. Permanent magnets
	f. Copper + zinc	vi. Precision measuring instruments

Q. Write the effects of acid rain on aquatic organisms and human beings.

Q. Name the process of converting crude oil obtained from seeds into commercially useful fuel.

Q. Gas A four times denser than gas B. Find the ratio between their rates of diffusion.

Q. How can ceramic articles be given a colored tinge?

Q. The correct equation of nuclear fusion reaction is

1. ${}_1{H}^1+{}_1{H}^1\to H_2$
2. ${}_1{H}^2+{}_1{H}^1\to {}_{2}H{e}^4+{}_0{n}^1$
3. ${}_1{H}^2+{}_1{H}^2\to {}_{2}H{e}^4+energy$
4. $2H_2+3H_2\to 5H_2$

Q. A tall plant with red flowers is crossed with a dwarf plant with white flowers. Which one of the following represents dwarf plant with white flowers?

1. ttrr
2. TrRr
3. TTrr
4. ttRr

Q. The normal thyroxine level in an adult is around $0.8ng/nl$ to $1.8ng/dl$. In a patient, it was $0.6ng/dl$. After a prolonged hormonal treatment, the thyroxine level was about $3.4ng/dl$. Mention the present symptoms of the patients.

Q. If the fermentation of molasses during the manufacturing of ethyl alcohol is delayed then the conclusion that can drawn is

1. Molasses is diluted
2. Molasses is not diluted
3. Temperature is maintained around 410 K
4. More yeast is added

Q. Write the balanced equations of chemical reactions taking under the following circumstances:
a. Steam is passed over red hot silicon. b. Silicon is burnt in air

Q. 'Roof top gardening may be a solution for both energy crisis and management of kitchen wastes'. Justify the statement.

Q. Mention any four characteristics features that are shared by humans with other primates.

Q. In which one of the following water conservation is high, as rate of transpiration is low?

1. 
   
2. 
   
3. 
   
4. 
   

Q. What is a solar cell?

Q. Mention any four features of Neanderthal man.

Q. Explain the structure of HIV

Q. Explain the process of industrial effluent treatment.

Q. Four Alternatives are suggested to each of the following questions/incomplete statements. Choose the most appropriate alternative and write the better of the choosen answer in the space provided against each questions.
The transformer among the following in which output voltage is more than the input voltage is

1. 
   
2. 
   
3. 
   
4. 
   

Q. Steam engines of Indian railways are replaced with diesel engine. Justify this move with two scientific reasons.

Q. Name two monosaccharide present in sucrose.