This statement is incorrect. Acceleration is not a scalar quantity, it is a vector quantity. It has both magnitude and direction.

Yes, it is correct. The string exerts a force that continuously causes the stone to deviate from the straight line path the stone's inertia would cause it to follow. When the string caeses to exert that force, the stone continues along the tangential path that it currently is following.

Yes, it is correct. Momentum  = M * V is directly proportional to velocity and kinetic energy is proportional to square of velocity. If the velocity is doubled,  the momentum is doubled and and kinetic energy becomes four times.

Yes, it is correct. It is the total force exerted by the body perpendicular to the surface.

Yes, it is correct. Relative density of solid is greater than water that means it is denser than water. Hence, it will sink.

Yes, it is correct. The use of lubricant makes the surface smooth and hence reduce the  friction. One of the lubricants is graphite powder, it fills the unevenness of the two surfaces and seperate them by forming a thin layer in between and so friction reduces.

Yes, it is correct. We are refering to velocity. Velocity is the speed in particular direction having both magnitude and direction. The change in displacement with time is velocity. It is a vector quantity.

Yes, it is correct. Seismic focus is the point of origination of earth quake waves. It lies within the crust of the earth.

Yes, this statement is incorrect. It is not at all safe to remain in open space or under a tree during lightning as it can catch fire.

Yes, it is correct. When the angle between two mirrors is right angle, the number of images formed is three. This is due to multiple reflection.

Yes, it is correct. When the body has more electrons than protons, it acquires negative charge.

Yes, it is correct. It uses 6 dots to represent letters and numbers.

Yes, it is correct as weight is a measure of the earth's gravitational pull on an object.

Yes, it is correct. Carbon dioxide itself is not a pollutant but excess carbon dioxide in the atmosphere traps the heat of Sun.

Yes, it is correct. The image is formed at the same distance behind the mirror as the object is in front of it.

Yes, it is correct because this statement does not explain that the effect of force is greater when area of contact is lesser. It shows that when force is applied on an object, it changes its shape.

Yes, it is correct. Smaller the area, larger is the pressure for a given applied force. One end of the nail is made sharp so as to produce large pressure on the area concerned.

Yes, it is correct. In running a machine, if friction is there in machine more power is required. As it produces heat in many parts of the machine, some useful energy is wasted as heat energy. Engines of automobiles consume more fuel which is a money loss.

Yes, it is correct. Eyes contain rod cells and cone cells. Rod cells are the nerve cells that are sensitive against dim light. Eye can sense objects because of rod cells and if the rod cells are less than normal value, the eye would not be able to see in dim light.

Yes, it is correct. Greater the depth, more is the pressure exerted by it.

Yes, it is correct. The junction of retina and optic nerve is called the blind spot as there are no sensory cells here and so no vision possible.

Yes, it is correct. Moon's gravitational force is lesser than that of earth. The mass remains unchanged but the weight changes which depends on gravitational force.

Yes, it is correct.The rough the surface, the greater the opposing force, i.e. friction. Oil acts as a layer between the two surfaces and so reduces the friction.

Yes, it is correct. Momentum is the product of mass and velocity of body and so quantity of motion.

Yes, it is correct. The positively charged particles, i.e. protons are firmly bound in the atom but electrons, i.e. negatively charged articles are loosely bound.