Science (English Medium) कक्षा १२ - CBSE Important Questions

Answer the following question:
Substantiate with the help of one example that in an ecosystem mutualists
(i) tend to co-evolve and
(ii) are also one of the major causes of biodiversity loss.

Given below is an equation describing the Species-Area relationship between species richness and area for a wide variety of taxa as angiosperm plants, birds, bats etc. S = CA^z

1. Give a graphical representation of the given equation showing Species-Area relationship.
2. What does 'S' represent in the given equation?
3. What is the value of 'Z' (regression coefficient) for frugivorous birds and mammals in the tropical forests of different continents?

Given below is a 'pie chart' representing the global biodiversity:

Proportionate number of species of major taxa.

1. Identify (X) and (Y) in the given 'pie chart'.
2. "Extinction of species across taxa are not random." Which group amongst the vertebrates is more vulnerable to extinction?
3. Give one example of each of the recent extinctions of species in Russia, Mauritius and Australia.

Write the inference drawn by Alexander von Humboldt after his extensive explorations of South American jungle.

Study the graph given below:

As per Alexander von Humboldt, what do the symbols S, A, Z and C in the graph stand for, in respect of a species and area relationship?

"Biodiversity plays a major role in many ecosystem services that nature provides."

Describe any two broadly utilitarian arguments to justify the given statement.

"Biodiversity plays a major role in many ecosystem services that nature provides."

State one ethical reason for conserving biodiversity.

Define van’t Hoff factor.

How many atoms constitute one unit cell of a face-centered cubic crystal?

What is the formula of a compound in which the element Y forms hcp lattice and atoms of X occupy 2/3^rd of tetrahedral voids?

Write two differences between an ideal solution and a non-ideal solution.

Why does a solution containing non-volatile solute have higher boiling point than the pure solvent ?

Why is elevation of boiling point a colligative property?

Calculate the freezing point of the solution when 31 g of ethylene glycol (C₂H₆O₂) is dissolved in 500 g of water.

(K_f for water = 1.86 K kg mol^–1)

Define the following term: Primitive unit cells

Define the following term:

Ferromagnetism

Henry’s law constant for CO₂ in water is 1.67 × 10⁸ Pa at 298 K. Calculate the quantity of CO₂ in 500 mL of soda water when packed under 2.5 atm CO₂ pressure at 298 K.

Define the term abnormal molar mass.

Write one difference in Solution and Colloid

Define the following term: 

Colligative properties