20 points 2 questions can you answer them
1 which of the following reactions is a synthesis reaction?
n2 + 3h2 → 2nh3
mgi2 + br2 → mgbr2 + i2
kclo3 → kcl + o2
hcl + naoh → nacl + h2o
2 suppose that the half-life of an element is 1000 years. how many half-lives will it take before one-eighth of the original sample remains?
8
125
12.5
3

Answer 1 : The synthesis reaction is,

Explanation :

Synthesis reaction : It is a type of reaction in which the reactants present in elemental state react to give a single product.

(1)

This is a synthesis reaction.

(2)

This is a single displacement reaction in which the most reactive element displaces the least reactive element.

(3)

This is a decomposition reaction in which larger reactant decomposes to give two or more products.

(4)

This is a neutralization reaction in which an acid and a base react to give a salt and water as a product.

Answer 2 : The number of half-lives it take will be, 3

Formula used :

where,

a = amount of reactant left after n-half lives =

= Initial amount of the reactant

n = number of half lives

Putting values in above equation, we get:

n = 3

Therefore, the number of half-lives it take will be, 3

explanation:

two years ago, when picking flowers in the mountains back of yosemite valley, i found a book. it was blotted and storm-beaten; all of its outer pages were mealy and crumbly. the paper seemed to dissolve like the snow beneath which it had been buried, however; many of the inner pages were well preserved. and although all were more or less stained and torn, whole chapters were easily readable. this is the condition of the great open book of yosemite glaciers today; its granite pages have been torn and blurred by the same storms that wasted the castaway book.

two years ago, when picking flowers in the mountains back of yosemite valley; i found a book. it was blotted and storm-beaten, all of its outer pages were mealy and crumbly. the paper seemed to dissolve like the snow beneath which it had been buried, however, many of the inner pages were well preserved. and although all were more or less stained and torn; whole chapters were easily readable. this is the condition of the great open book of yosemite glaciers today, its granite pages have been torn and blurred by the same storms that wasted the castaway book.