Answer:
0.605 molal
Explanation:
molality is the amount of solute in a particular mass of solvent.
lets calculate the amount of benzene solute.
mass of benzene= 13.3g
molar mass of C6H6= 12*6 +1*6 =72+7=78g/mol
amount of benzene= mass/molar mass
=13.3/78
=0.1705mol
molality= amount of solute/mass of solvent in kg
mass of solvent=282g=0.282kg
molality = 0.1705/0.282
=0.605 molal
Answer:
The answer to the question is
50 % of the original amount of potassium 40 will be left after one half life or 1.25 billion years
Explanation:
To solve the question we note that the half life is the time for half of the quantity of substance that undergoes radioactive decay to disintegrate, thus
we have
half life of potassium 40 K₄₀ = 1.25 billion years
To support the believe tht the rock was formed 1.25 billion years ago we have
After 1.25 billion years we have
= 
=0.5 of 
will be left or 50 % of the original amount of potassium 40 will be left
<span>Radioactive waste, as its name implies, is a source of radiation that can be harmful to living organisms. Therefore it needs to be disposed of very carefully in such a way that the radiation cannot reach human beings and other living organisms. One method to do this is to bury the waste in deep pits. </span>
Answer: A) Na+ and O2-
Explanation:
To know the electronic configuration, one has to determine the numbers of electrons present in each atom.
Na+ means a sodium atom that has lost one valence electron. A Sodium atom initially has 11 electrons, but having lost an electron making it 10 electrons remaining with electron configuration of 1s2 2s2 2p6.
O2- means oxygen atom that has gained two valence electrons. An oxygen atom initially has 8 electrons, having gained two electrons makes it 10 electrons with electron configuration of 1s2 2s2 2p6. same as Na+
The purpose of gaining or losing electrons is to attain a stable duplet or octet structure.
