Physical or chemical change? (a) a piece of copper is hammered to a different shape. (b) frost is formed when solid surfaces are cooled to below the dew point. (c) microorganisms decompose nitrate from the soil to form nitrogen gas. (d) as air temperature rises, its ability to hold water vapor increases significantly. (e) nitrous oxide is produced by the combustion of gasoline in industrial processes. (f) with the of sunlight, photosynthesis produces oxygen when carbon dioxide and water are chemically converted into glucose.

a) Physical change

b) Physical change

c) Chemical change

d) Physical change

e) Chemical change

f) Chemical change

Explanation:

Physical Change:

Type of change in which no new substance is formed, only change in shape or physical state is occur. Physical change can be reversed by reversing the condition.

Chemical Change:

A type of change in which new substance is formed and the change occured cannot be reversed.

A) A piece of copper is hammered to a different shape. Physical change

In this change, only shape of copper is changed.

(b) Frost is formed when solid surfaces are cooled to below the dew point. Physical change

Here, water vapour are changed to ice, i.e. change in physical state.

(c) Microorganisms decompose nitrate from the soil to form nitrogen gas. Chemical change

In this change, a new substance is formed.

(d) As air temperature rises, its ability to hold water vapor increases significantly. Physical change

No new substance is formed.

(e) Nitrous oxide is produced by the combustion of gasoline in industrial processes. Chemical change

New substance, nitrous oxide is produced.

(f) With the help of sunlight, photosynthesis produces oxygen when carbon dioxide and water are chemically converted into glucose. Chemical change

New substances are formed in this change.

given data:

determine the horse power (h.p) = ?

force applied to move the box(f) = 10 pounds,

box lifted from a distance         (d) = 3 feet

time taken to lift                         (t) = 10 sec,

the horse power is defined as amount of work required to move a load. the horse power is equal to 550 foot-pound per second

                  1 h.p   = 550 foot-pound/second

it can also be defined as the the load that need to be move a body for certain distance in a certain amount of time.

mathematically,

                      h.p = (force × distance)/ time

                            = (10 × 3)/ 10

                            = 30/10

                            = 3 foot -pound/sec

hence, the horse power is needed to move the box is 3 foot-pound/second

important note: 1 h.p = 550 foot-pound/second = 746 watts