there are 92 naturally occuring elements
Answer:
here
Explanation:
What is the total mass of $$3.01 x 10^23$$ atoms of helium gas?
✓ Well $$"Avogadro's number"$$ of helium atoms has a mass of $$4.0*g$$. Explanation: And $$"Avogadro's number"$$
Answer: Precision means that measurements are close to each other . Accuracy means that measurements are close to accepted value
Explanation:
Precision refers to the closeness of two or more measurements to each other.
For Example: If we weigh a given substance five times and you get 5.0 kg each time. Then the measurement is very precise.
Accuracy refers to the closeness of a measured value to a standard or known value.
For Example: If the mass of a substance is 5.0 kg and one person weighed 4.9 kg and another person weighed 3.9 kg. Then, the weight measured by first person is more accurate.
Thus Precision means that measurements are close to each other . Accuracy means that measurements are close to accepted value.
1a. calcium chloride (CaCl2)
b. 2HCl (aq) + Ca(OH)2 (s) —> CaCl2 (aq) + 2H2O (l)
i’m not sure about the rest but i hope this helped ^^
Answer:
B. materials change their properties.
Explanation:
In a chemical change, materials often change their properties because a re-arrangement of atoms takes place.
A chemical change is one in which new kind of matter is formed.
It is always accompanied by energy changes.
- Chemical changes are not reversible.
- They lead to the production of new kinds of matter
- It involves mass changes
- Requires considerable amount of energy
