Answer:
Groups show similar chemical properties about the elements
Explanation:
The periodic table is divided into groups and periods. Groups are vertical while periods are horizontal.
All elements in the same group possess the same number of outermost shell electrons. This number of outermost shell electrons controls the reactivity of the elements in the group.
Hence, groups show similar chemical properties of the elements in them, Groups separate elements into families which assist in the speedy study of elements.
Answer:
Option E, Half life = 
Explanation:
For a first order reaction, rate constant and half-life is related as:
Where,
= Half life
k = Rate constant
Rate constant given = 
So, the correct option is option E.
5 Na molecules and 5 Cl molecules
Answer:
Its the bottom one :) ......
<span>The density of the solution =1.05 g/ml.
</span><span>The total mass of the resulting solution is = 398.7 g (CaCl2 + water)
</span>
Find moles of CaCl2 and water.
Molar mass of CaCl2 = 110 (approx.)
Moles of CaCl2 = 23.7 / 110 = 0.22
so, moles of Cl- ion = 2 x 0.22 = 0.44 (because each molecule of CaCl2 will give two Cl- ions)
Moles of water = 375 / 18 = 20.83
Now, Mole fraction of CaCl2 = (moles of CaCl2) / (total moles)
total moles = moles of Cl- ions + moles of Ca2+ ions + moles of water
= 0.44 + 0.22 + 20.83
=21.49
So, mole fraction = 0.44 / (21.49) = 0.02
Guess what !!! density is not used. No need
