the correct answer is A.
Each atom has three sub particles, which are electron, proton and neutron. To get the atomic mass for each atom, one has to add the masses of the proton, neutron and electron in an atom. For each atom, the major contributors to its mass are proton and neutron, this is because the mass of the electron is very small indeed. Thus, the atomic mass of an element is usually in the range of its mass number, which is obtained by the summation of proton and neutron. Since it is the number of proton that indicate an atomic number and it is the mass number that indicate atomic mass, therefore, atomic mass can be greater than the atomic number.
0.4M is the concentration of a solution formed when 4.00 grams of sodium hydroxide is dissolved to make a 250cm cubed solution.
Molar concentration, also known as molarity, quantity concentration, or substance concentration. Molarity is a unit used to describe the amount of a substance in a solution expressed as a percentage of its volume. The number of moles per liter, denoted by the unit symbol mol/L or mol/dm³ in SI units, is the most often used unit denoting molarity. Because the volume of most solutions very minimally changes with temperature owing to thermal expansion, using molar concentration in thermodynamics is frequently not practical.
The formula for molarity,
Molarity = (moles/vol) x 1000
=
x 1000
= (0.1 / 250) x 1000
=0.4M
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Answer:
mass ratio of A/B is 2:1
Explanation:
Since the mass of box A = 10g
mass of box B = 5g
Mass of box C = mass of box A + mass of box
A ratio compares two quantities. To find the ratio of the two boxes:
Ratio of A to B = 
Ratio of A to B =
= 2
The mass ratio is 2:1 i.e box A has twice the mass of B
Ponds are most likely to dry up
The answer is C. Valence Electrons