Answer:
pure hydrogen is a pure substance even though it consists of many different types of molecules. what makes it pure substance is that it is free from contamination.
Explanation:
de Broglie wavelength= h/mv
v=h/m x de Broglie wavelength
v= (6.626× 10^-34)/ (2347× 1.27 × 10^-38)
v= 22.229 m/s(according to Google scientific calculator)
am sorry I don't hv a calculator at hand
Answer:
According to mass and volume, block density is 2 g/ml
Explanation:
Density is a measure, usually used in physics and chemistry, that relates the mass and volume of a solid or compound.
In general terms, the density is directly proportional to the mass, and inversely proportional to the volume, so increasing the mass will also increase the density.
The formula used to calculate the density is
ρ = 
Therefore, according to the mass and density of the block
ρ =
= 2g/ml
Being the density of the block equal to 2 g/ml.
<em>The other options are not possible, because the values given do not correspond to the result of the equation.</em>
Answer:
Double Displacement Reaction
Explanation:
A double displacement reaction is a type of chemical reaction in which the reactant ions exchange places to form new products. Usually, a double displacement reaction results in precipitate formation.
I think you forgot to give the options along with the question. I am answering the question based on my knowledge and research.All scientific theories <span>must be based on careful and rational examinations of the facts. I hope that this is the answer that you were looking for and it has actually come to your help.</span>