If the half-life of a sample of a radioactive substance is 30 seconds, how much would be left after 60 seconds? <span>
A. one-fourth</span>
<h2><em>1. A</em></h2><h2><em>3. B</em></h2><h2><em>4. C</em></h2><h2><em>7. E</em></h2><h2><em>5. F</em></h2>
The valves stop the blood from flowing backwards
The molar mass is usually referred to with
M
, while the mass is referred to as
m
. The amount of substance is
n
. This gives you the following relationship:
=
M
=
m
n
Since you have given (C3H8)=11 g
m
(
C
3
H
8
)
=
11
g
and you already looked up (C3H8)=44.1 gmol−1
M
(
C
3
H
8
)
=
44.1
g
m
o
l
−
1
, you can use this formula to determine (C3H8)
n
(
C
3
H
8
)
.
In this question it is quite hard to explain the use of significant figures. Those are used to imply a certain inaccuracy. Not enough information is given by the question, as of how accurate the measurement is. It is a mere exercise of converting one property into another. Here you should not worry about it.
There are 6 atoms of oxygen on the reactant side of the following equation: 2Fe2O3 + 3C → 4Fe + 3CO2. Details about atoms can be found below.
<h3>How to find number of atoms?</h3>
The number of atoms of an element in a balanced equation is the amount of that element involved in the reaction.
According to this question, Iron oxide reacts with carbon to produce iron and carbon dioxide as follows:
2Fe2O3 + 3C → 4Fe + 3CO2
In this reaction, 2 × 3 atoms = 6 atoms of oxygen are present on the reactant side of the equation.
Learn more about number of atoms at: brainly.com/question/8834373
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