Answer:
0.808 M
Explanation:
Using Raoult's Law

where:
= vapor pressure of sea water( solution) = 23.09 mmHg
= vapor pressure of pure water (solute) = 23.76 mmHg
= mole fraction of water
∴






------ equation (1)
------ equation (2)
where;
number of moles of sea water
number of moles of pure water
equating above equation 1 and 2; we have :



NOW, Molarity = 



As we assume that the sea water contains only NaCl, if NaCl dissociates to Na⁺ and Cl⁻; we have 
The answer is D, medical diagnosis
The d-block elements are found in groups 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 of the periodic table.
So your answer is A) Transition metals
Answer:
If it loses 2 electrons, the net charge on the atom will be 2+
If the atom instead gains 4 electrons, the net charge will be 4-
Explanation:
It is based on adding and subtracting charges. Protons are +1 and electrons are -1
If the atom has 9 protons and 9 electrons, the net charge is +9 + (-9) = 0. The +9 is the 9 protons and the -9 is from the 9 electrons.
If two electrons are taken away, there would be 9-2 or 7 electrons with 9 protons. The net charge would then be +9 + (-7) = +2. +9 comes from the 9 electrons and -7 is from the 7 electrons.
So, if two electrons are taken away, the net charge is +2.
Similarly, if the atom gains 4 electrons, there will be 9+4 or 12 electrons and 9 protons. The net charge would then be +9 + (-12) = -4. +9 comes from the 9 protons and -12 comes from the 12 electrons.
So, if 4 electrons are added, the net charge is -4.