Answer: a. solution
Explanation:
A solution is a mixture which contains two or more than two types of components and they can be separated by physical means as well.Example: salt water
Molecule of an element is defined as the aggregate of atoms of similar elements. Example: 
. Molecule of a compound is the aggregate of atoms of different elements in a fixed ratio by mass. Example: 
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: 
A pure substance is a substance which contains definite composition of only one type of component. Hence, it cannot be separated by physical means. Example: Helium, water
Answer: 8.1 days
Explanation:
Expression for rate law for first order kinetics is given by:
where,
k = rate constant
t = age of sample
a = let initial amount of the reactant = x
a - x = amount left after decay process= 
a) to find rate constant
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
b) for completion of one fourth of reaction
Thus after 8.1 days , one fourth of original amount will remain.
Answer:A fossil is the remains or traces of a once-living plant or animal that was preserved in rock or other material before the beginning of recorded history. ... Fossils of single-celled organisms have been recovered from rocks as old as 3.5 billion years. Animal fossils first appear in rocks dating back about 1 billion years.
Explanation:
Answer:
34.2 g is the mass of carbon dioxide gas one have in the container.
Explanation:
Moles of 
:-
Mass = 49.8 g
Molar mass of oxygen gas = 32 g/mol
The formula for the calculation of moles is shown below:
Thus,
Since pressure and volume are constant, we can use the Avogadro's law as:-
Given ,
V₂ is twice the volume of V₁
V₂ = 2V₁
n₁ = ?
n₂ = 1.55625 mol
Using above equation as:
n₁ = 0.778125 moles
Moles of carbon dioxide = 0.778125 moles
Molar mass of = 44.0 g/mol
Mass of = Moles × Molar mass = 0.778125 × 44.0 g = 34.2 g
<u>34.2 g is the mass of carbon dioxide gas one have in the container.</u>
