Some countries now use alcohol as an additive in petrol. In context of this, consider the following statements:
1. Addition of alcohol increases the burning efficiency of petrol and reduces knocking.
2. Petrol added with small quantities of alcohol becomes more stable and doesn’t become too hot in warm areas or too cold in freezing temperatures.
3. Alcohol is a cleaner fuel which gives rise to only carbon dioxide and water on burning in sufficient oxygen.
Which of the statements given above is the correct reason for using alcohol as an additive in petrol?
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Desirable characteristics of a crop variety helps in easy adoption of that crop by the farmers. In this context, consider the following statements:
1. Incorporating desirable characters into crop varieties can be done through fertilisation.
2. Dwarfness is desired in cereals, so that less nutrients are consumed by these crops.
3. Hybridisation refers to crossing between genetically similar plants.
Which of the statement(s) given above is/are correct?
Read the following statements carefully and select the correct answer from codes given below:
1. The phenomenon of splitting of white light into its seven component colours by a prism is called dispersion.
2. While passing through a prism, the violet light bends the least while the red the most.
3. Isaac Newton was the first to use a glass prism to obtain the spectrum of sunlight.
Which of the statements given above is/are correct?
The presence of certain minerals is essential in water, however, if found in excess they can be harmful to our body. In this context, which of the following statements are correct?
1. Deficiency of fluoride in drinking water causes diseases such as tooth decay.
2. Excessive sulphate in drinking water causes laxative effect.
3. Excess lead in drinking water can cause disease such as ‘blue baby’ syndrome.
Select the correct answer using the code given below.
Which of the following statement(s) about Acquired Immuno Deficiency Syndrome (AIDS) is/are correct?
1. AIDS is a congenital disease caused by a retrovirus known as Human Immuno deficiency Virus (HIV).
2. AIDS is characterised by a progressive decrease in the number of T-lymphocytes in the body of the infected person.
Select the correct answer using the code given below.
Which among the following are the characteristic features of birds?
1. They are cold-blooded animals.
2. They lay eggs.
3. Two forelimbs are modified for flight.
4. They breathe through lungs.
Select the correct answer using the code given below:
Which of the following phenomena are caused due to ‘atmospheric refraction’?
1. Flickering of objects seen through a turbulent stream of hot air rising above a fire.
2. The reddening of the sun at sunrise and the sunset.
3. The apparent flattening of the Sun’s disc at sunrise and sunset.
4. The Sun is visible to us about 2 minutes before the actual sunrise, and about 2 minutes after the actual sunset.
Select the correct answer using the code given below.
Consider the following statements:
1. Exchange of gases in plants occurs not only across the surface of leaves but also across the surface of stems and roots.
2. Plant close its pores known as the Stomata, when they do not need carbon dioxide for photosynthesis.
3. Guard cells present in plants are responsible for controlling the movement of water in them.
Which of the statements given above is/are correct?
The immune system is a complex network of cells known as immune cells that contains lymphocytes. In this context, consider the following statements:
1. Lymphocytes are red blood cells and one of the body's main types of immune cells.
2. Lymphocytes are made in the bone marrow and found in the blood and lymph tissue.
Which of the statements given above is/are correct?
Consider the following statements about ‘Human Body’:
1. Muscles contain special proteins which contract and relax to cause movement.
2. We can control the movement of all the muscles in our body.
Which of the statement(s) given above is/are correct?
With reference to ‘blood’ present in the human body, consider the following statements:
1. It carries oxygen and food to all the cells in human body.
2. It collects wastes from the cells for disposal.
3. It is a type of connective tissue.
Which of the statements given above is/are correct?