Answer:
<h3>The answer is 8.29 %</h3>
Explanation:
The percentage error of a certain measurement can be found by using the formula

From the question
actual density = 19.30g/L
error = 20.9 - 19.3 = 1.6
We have

We have the final answer as
<h3>8.29 %</h3>
Hope this helps you
Answer:
Increasing atomic number - True
Explanation:
The modern table is based on Mendeleev’s table, except the modern table arranges the elements by increasing atomic number instead of atomic mass.
The Atomic number is the number of protons in an atom, and this number is unique for each element. For example, Hydrogen has an atomic number of 1, Calcium has an atomic number of 20.
In the modern periodic table the elements are further arranged into:
- rows, called periods, in order of increasing atomic number. Elements in the same periods have the same number of shells.
- vertical columns, called groups, where the elements have similar properties. Elements in the same group has the same number of valency (outermost number of electrons)
Exothermic reaction releases energy in the form of heat or light
Answer: The correct option is B.
Explanation: To describe the motion of an object, we use the equations of motion.



From the above equations, we require position, speed and direction through which we an calculate the displacement, velocity and acceleration.
To calculate the complete motion of an object, we require all the three factors.
Hence, the correct option is B.