A) Second
Second is the base unit of time.
Answer:
The percentage is k
%
Explanation:
From the question we are told that
The mass of the stibnite is 
The volume of KBrO3(aq) is 
The concentration of KBrO3(aq) is 
Now the balanced ionic equation for this reaction is

The number of moles of
is

substituting values


from the reaction we see that 1 mole of
reacts with 3 moles of 
so 0.003325 moles will react with x moles of 
Therefore


Now the molar mass of
is a constant with a values of 
Generally the mass of
is mathematically represented as

substituting values

The percentage of Sb(antimony) in the overall mass of the stibnite is mathematically evaluated as
k 
k
%
Answer:

Explanation:
Hello!
In this case, since the density is defined as the degree of compactness of a substance, and is defined as the mass over the volume:

Given the dimensions of the bar of lead, we can compute the volume as shown below:

Thus, the density turns out:

Best regards!
Answer:
Which scientist developed the first model of the atom that showed the structure of the inside of an atom
Ernest Rutherford