How are covalent bonds formed?

Define electropositivity.

OR

The atomic radii of first group elements are given below:

Answer question numbers 3(a) to 3(d) on the basis of your understanding of the following paragraph and the related studies concepts.

The Tehri dam is the highest dam in India and one of the highest in the World. The Tehri dam withholds a reservoir of capacity 4.0 km³ and surface area 52 km². It is used for irrigation, municipal water supply and the generation of 1000 MW of hydroelectricity.

The Tehri Dam has been the object of protests. Environment activist Shri Sunder Lal Bahuguna led the "Anti Tehri Dam Movement" from 1980s to 2014. The protest was against the displacement of town inhabitants and environmental consequences of the weak ecosystem. The relocation of more than 1,00,000 people from the area has led to protracted legal battles over resettlement rights and ultimately resulted in the delayed completion of the project.

(a) How is hydropower harnessed?

(b) Define 1 MW.

(c) Mention two disadvantages of constructing Tehri Dam.

(d) What happens when water from great heights is made to fall on blades of turbine?

Question number 4(a) to 4(d) are based on table given below. Study the table in which the levels of Thyroid Stimulating Hormone (TSH) in women are given and answer the questions that follow on the basis of understanding of the following paragraph and the related studied concepts.

Women are at greater risk for developing abnormal TSH levels during menstruation, while giving birth and after going through menopause. Around 5% of women in the United State have some kind of thyroid problem compared to 3% of men. Despite claims that high TSH increases your risk for heart diseases. But a 2017 study showed that older women are especially at risk for developing thyroid cancer if they have high TSH levels along with thyroid nodules.

(a) A 35 years old women has TSH level 6.03 mU/L. what change should she bring in her diet to control this level?

(b) When do face a greater risk of abnormal TSH level?

(c) State the consequence of low TSH level.

(d) Name the mineral that is responsible for synthesis of hormone secreted by thyroid gland.

The sky appears dark to passengers flying at very high altitudes mainly because: