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.
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Which among the following method(s) is/are used by pests to attack crops sown in the field?
1. They attack the root of the plant.
2. They bore into stem and fruits of the plant.
3. They suck water from various parts of the plant.
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Read the following statements carefully and select the correct answer from codes given below:
1. Working of electric motors involves the electric effect of electric current.
2. Working of electric generators involves the magnetic effect of moving magnets.
Which of the statement(s) given above is/are correct?
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?
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?
With reference to the uses of ‘concave mirrors’, read the following statements carefully:
1. They are commonly used in vehicles headlights to get powerful parallel beams of light.
2. They are often used as shaving mirrors to see a larger image of the face.
3. They are fitted on the sides of the vehicle to have a wider field of view.
4. Large concave mirrors are used to concentrate sunlight to produce heat in solar furnaces.
Which of the statements given above is/are correct?
Vectors are living organisms that can transmit infectious pathogens between humans, or from animals to humans. The commonest vectors we all know are mosquitoes. Which among the following vector borne diseases are caused by mosquitoes?
1. Yellow Fever
2. Lymphatic Filariasis
3. Zika Fever
4. Japanese Encephalitis
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Consider the following statements about ‘Biochemical Oxygen Demand’ (BOD):
1. It is the amount of oxygen required by bacteria to break down the organic matter present in a certain volume of a sample of water.
2. Highly polluted water have BOD value of less than 5 ppm.
Which of the statements given above is/are correct?
When light enter the human eye, it passes through the different parts of the eye. In this context arrange the following in the correct sequence:
Consider the following statements:
1. Tendons are type of connecting tissue that connect muscles to bones.
2. Nerve impulses are transmitted with the help of tendons throughout our body.
Which of the statement(s) given above is/are correct?
Unicellular organism are unique because they are made up of a single cell only. Which of the following is/are examples of unicellular organisms?
1. Amoeba
2. Yeast
3. Bacteria
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