Allen and Annie travel at x m/s and ym/s
respectively. If the distance covered by
both of them is the same, what is the ratio
of the time taken by Allen to that of
Annie?
a. :
b. y:2
C. 1-2:34
d. y-2:1
Answers
Answer:
Give reason for the following observations.
(a) Naphthalene balls disappear with time leaving any solid.
(b) We can get the smell of perfume sitting several metres away.
a) Naphthalene balls disappear with time without leaving any solid.
Naphthalene undergoes sublimation easily, i.e., the change of state of naphthalene from solid to gas without the intervention of the liquid state. Thus, naphthalene balls keep forming naphthalene vapours that disappear into the air with time without leaving any soli
(b)We can get the smell of perfume sitting several metres away.
Perfume has a higher degree of vaporization
,and its vapour diffuses into the air easily. Gaseous particles possess high speed and move very rapidly in all directions. When perfume sprayed, its particles diffuse into the air particles at a high-speed rate and reach our nostrils. This enables us to smell the perfume from a distance.