A is 1. Each letter corresponds to what place they are in the alphabet
Answer:
Isotopes of an element have same number of protons but different number of neutrons. Which means isotopes of an element have same atomic number but different mass number.
The chemical property of an element is determined by the number of electrons. And as all the isotopes have same number of electrons, they have same chemical properties.
Thus as isotopes of an element have same atomic number , they have same number of electrons and protons. As they have different mass number, the number of neutrons will be different. Hydrogen has three isotopes , 
, 
and 
. Thus has no neutron.
The question is incomplete, the complete question is;
In the 1800s, a popular belief known as vitalism stated that life processes could not be explained by the laws of physics and chemistry,and were instead dictated by an independent life force. Which discovery most likely caused scientists to revise this hypothesis regarding the origin of life on Earth?
a. that inorganic compounds existed within live organisms
b. that organic compounds could be synthesized in a laboratory
c. that RNA could serve as a template to synthesize DNA
d. that self-replicating molecules existed inside cells
Answer:
b. that organic compounds could be synthesized in a laboratory
Explanation:
Vitalism is the belief that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things"(wikipedia).
This theory held that the molecules involved in life processes could not be synthesized in the laboratory.
All these were upturned after Fredrich Whöler's synthesis of urea in 1828. He was able to show that molecules involved in life process can also be synthesized in the laboratory. This gave rise to modern synthetic organic chemistry.
Kepler's Laws of Planetary Motion. While Copernicus rightly observed that the planets revolve around the Sun, it was Kepler who correctly defined their orbits.
Sorry about the holds, copied it from google...
<h2>
Answer:True</h2>
Explanation:
Heterogeneous mixture is a mixture with non-uniform composition.
The properties of the mixture like concentration may change for different parts of the mixture.
Colloids contain solute particles of size 
.The presence of these particles makes the mixture heterogeneous.
Suspensions contain solute particles of size 
.These particles settle to the bottom of the mixture which makes the composition of the bottom different from the top.
So,colloids and suspensions are two types of heterogeneous mixtures.
