Answer:
1 - 3
Explanation:
- Look to see where metals are on the periodic table then look at what group they are in. The group tells you the number of valence electrons. Ex. 1A has one valence electron.
- Hope this helped! If you need a further explanation please let me know.
Answer:
The half life is 
Explanation:
The half life of a first order reaction is mathematically represented as
Substituting 
for the rate constant
Answer:
1.23 M
Explanation:
Molarity of a substance , is the number of moles present in a liter of solution .
M = n / V
M = molarity
V = volume of solution in liter ,
n = moles of solute ,
Moles is denoted by given mass divided by the molecular mass ,
Hence ,
n = w / m
n = moles ,
w = given mass ,
m = molecular mass .
From the question ,
w = given mass of NaCl = 7.2 g
As we know , the molecular mass of NaCl = 58.5 g/mol
Moles is calculated as -
n = w / m = 7.2 g / 58.5 g/mol = 0.123 mol
Molarity is calculated as -
V = 100ml = 0.1 L (since , 1 ml = 1/1000L )
M = n / V = 0.123 mol / 0.1 L = 1.23 M
The atomic mass of an element on the periodic table is the weight of 1 mole of atoms. For example, the atomic mass of Fe is 55.8 on the periodic table. If you weigh out 55.8 grams of Fe you will have 1 mole of iron, or 6.02 x 1023 atoms.
3rd Answer. Rays reflect in random directions
