In winter, in the industrialised and metro cities, especially in the morning hours, the visibility is greatly lowered due to the formation of a dark fog, generally resulting in serious road accidents. It also causes suffocation.
$(a)$ What does this indicate and also name this phenomenon?
$(b)$ How is this phenomenon produced? Name two gases which cause acid rain.

State two advantages of composite fish culture. What is the application of hormonal stimulation in fish culture?

What is the advantage of green manure?

$(a)$ What is lactation period? Name two breeds of cattle which are selected for their long lactation period. Why are they crossed with local breeds?
$(b)$ What are roughage and concentrates?

$(a)$ Distinguish between macronutrients and micronutrients on the basis of $(i)$ their functions and $(ii)$ amount required by plants. $(b)$ Classify the following elements as macro or micronutrients in plants: $(i)$ Nitrogen,$(ii)$ Zinc,$(iii)$ Copper,$(iv)$ Potassium. $(c)$ In what way is the deficiency of these nutrients harmful to crops?

While studying about irrigation in her textbook,Bhanika read that proper irrigation is very important for the success of crops. Ensuring that the crops get water at the right stages during their growing season can increase the expected yields of any crop. She then thought about how irrigation is necessary in daily life,and considered sources like wells,rivers,and tanks as irrigation systems. She also shared this knowledge about irrigation systems with her friends.
$(a)$ According to you,what kind of qualities are seen in Bhanika?
$(b)$ Explain how rivers are an effective irrigation system.