Answer: (D) Over grazing by cattle will not help in soil conservation but will result in soil erosion. As plant roots hold the soil tightly thus they prevent its erosion. When plant over is removed by overgrazing, soil erodes away.
Which of the following statements is false regarding physical and chemical properties?
A The composition of matter need not be changed for observing a physical change.
B During a chemical reaction, molecules undergo a change and their concentration keeps decreasing along with time.
C Chemical property is the ability of matter to undergo some chemical change because of its composition.
D During a chemical reaction, same molecules are present throughout the change.
Sakshi performs a chemical reaction in the laboratory. The change in the position of the molecules is represented in the given figure.
Which of the following chemical reactions was performed by Sakshi?
ACaO (aq) + CO2 (g)--->CaCO3 (aq)
B2H2 (g) + O2(g)--->2H2O (l)
CNa (s) + O2 (g) ---> Na2O (s)
DH2 (g) + Cl2 (g)---> 2HCl (g)
Landowner of a village has decided to use one of his fields which had factories for several years for the production of crops. With which of the following substances does he need to treat his field for a long time to fulfill his purpose?
DBoth B and C
Lime is used to make acidic soil neutral. It is not clear from this question how the soil is acidic.
What should a car-driver do to reduce the pollution caused by his car?
ARun car on diesel instead of petrol.
BUse catalytic converter in car.
CTie plastic bag around the exhaust pipe.
DNone of these
too much to expect me to know what a catalytic converter..