Heredity and Evolution — Science STD 10 — Question

What are the advantages and disadvantages of using a solar cooker?

What is hypertension? Why is it caused? What harm can it do?

A magnesium ribbon is burnt in oxygen to give a white compound X accompanied by emission of light. If the burning ribbon is now placed in an atmosphere of nitrogen, it continues to burn and forms a compound Y.

1. Write the chemical formulae of X and Y.
2. Write a balanced chemical equation, when X is dissolved in water.

Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents like ethanol also?

What is meant by pollination? Name and differentiate between the two modes of pollination in flowering plants.

What are the two ways in which cow-dung can be used as a fuel? Which of them is better and why?

P, Q, R and S are four major types of phytohormones. P is a phytohormone which functions mainly as a growth inhibitor. It promotes the wilting and falling of leaves. Q, R and S are phytohormones which all promote growth of plants in various ways. Q is responsible for the phenomenon of phototropism in plants. R is involved mainly in shoot extensions. The phytohormone S helps in breaking the dormancy of seeds and buds. What are P, Q, R and S? Give one reason each for your choice.

"If there were no algae there would be no fish in the sea." Comment.

How does our body respond when adrenaline is secreted in large amounts into the blood?

1. Draw a ray diagram to show the refraction of light through a glass slab and mark angle of refraction and the lateral shift suffered by the ray of light while passing through the slab.
2. If the refractive index of glass for light going from air to glass is 3/2, find the refractive index of air for light going from glass to air.