Ca + 2h2o --> ca(oh)2 + h2
40g of ca is mixed with 100g of water. calculate mass of solution left after reaction is complete.

Explanation:

Ca(s) + 2H₂O(ℓ) ⟶ Ca(OH)₂(s) + H₂(g)

Mass of reactants = mass of products

You have 140 g of reactants, so you should get 140 g of products.

The calcium hydroxide and the left-over water will remain in the beaker, but the hydrogen will escape.

According to  the equation, 1 mol (40 g) of Ca produces 1 mol (2.0 g) of hydrogen.

Mass of suspension + mass of hydrogen = 140    g

                           Less mass of hydrogen =    2.0 g

                                 Mass of suspension = 138    g

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.  

all eukaryotic cell have mitochondria : )