William finds a piece of pure iron in his garden. After a few days, the iron begins to rust. What are the two types of substances involved in the rusting process of iron?
Iron is
with one kind of atom that combines with oxygen from the air to form rust (iron oxide). Rust contains two types
of atoms, which means it is

ITS MULTI Rust

Explanation:

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.

3. dark matter

empty space could also be a simple vacuum