Answer:
The period 4 alkaline-earth metal has the name Calcium. An isotope of this element having 20 neutrons has a mass number of 40.
Explanation:
Looking at the periodic table 4th row for the alkaline-earth metal, we can find Calcium which has an atomic number of 20 (or protons number, or z). The mass number is given by the sum of protons and neutrons. If the number of protons in this case is 20 and the number of neutrons is also 20, the mass number A = 40.
yes substances Do react by mass
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Answer: An element is a pure substance. It can not easily be broken down into parts by physical means.
A)True
B)False
<u>The answer is true. </u>
<span>For number
two, the equation is balanced. Na in the reactant side has one atom and also in
the product side. O has only one atom in the product and in the reactant. There
are 2H’s in the reactant and in the product side (present in H2O, the 2 in H
stands for 2 atoms of H). One atom of Cl is present in the reactant and product
side.</span>
For number
three, the reactants are NaOH-sodium hydroxide and HCl-hydrogen
chloride(hydrochloric acid). The products are NaCl-sodium chloride and
H2O-water.
