Answer:
B) They will react because X and Y can share two pairs of electrons to become stable
Explanation:
The electron configurations of two elements x and y are given :
X: 1s2 2s2 2p6
Y: 1s2 2s2 2p6 3s2 3p6
The statement that is true for both the elements is that, they both will react as they both can share two pairs of electrons to become stable.
To become stable the outermost shell or p orbital should have 8 electrons, so element X can gain 2 atoms to become stable.
Element Y can also react as it can also share two atoms to fulfill its 3p orbital and will stable.
Hence, the correct option is "B".
Answer:
, zirconium-103.
Explanation:
In a nuclear reaction, both the mass number and atomic number will conserve.
Let 
represent the unknown particle.
The mass number of a particle is the number on the upper-left corner. The atomic number of a particle is the number on its lower-left corner under the mass number. For example, for the particle , 
is the mass number while 
while is the atomic number.
Sum of mass numbers on the left-hand side of the equation:
.
Note that there are three neutrons on the right-hand side of the equation. Sum of mass numbers on the right-hand side:
.
Mass number conserves. As a result,
.
Solve this equation for :
.
Among the five choices, the only particle with a mass number of 103 is . Make sure that atomic number also conserves.
Answer:
More exactly this number is 6.02 x 1023 10 2 3 .
<span>The 80 ml solution has (.04)(80) ml of the medicine, or 3.3 ml of medicine.The pharmacist adds V ml of 7% solution, or .07V ml of medicine. The total amoune of medicine is (.07V + 3.2) mg.
The total volume of solution is (V + 80) ml, so
(.07V + 3.2) / (V + 80) = .05. Solve for V.</span>
