6. Which phase of matter has a definite volume and shape. a. solid
b. liquid
c. gas
d. plasma

solids

Explanation:

beacause if you take an ice cube does it change its shape no and if it has a definite shape it is sure to have a definite volume

photocells convert light energy to electricity

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.