Answer:
A
Explanation:
beacause in both the electronegativity values and number of first she'll electrons
Answer:
10.5grams
Explanation:
Molarity = number of moles (n)/ volume (V)
According to this question;
Volume = 750 mL = 750/1000 = 0.75L
Molarity = 0.35M
number of moles (n) = molarity × volume
n = 0.35 × 0.75
n = 0.2625mol
Using mole = mass/molar mass
Molar Mass of NaOH = 23 + 16 + 1
= 40g/mol
mole = mass/molar mass
0.2625 = mass/40
mass = 10.5grams
10.5 grams are needed to prepare 0.75L of a 0.35 M solution of NaOH.
By nuclear fusion of hydrogen nuclei into Helium
Answer:
76
Explanation:
Alpha decay is one of the most basic forms of radioactive decay. It has an atomic mass of 4 and a proton number of two.
Undergoing an alpha decay will decrease the atomic mass by four and the atomic number by two.
In this particular question, we are particular about the atomic number. The atom has an atomic number of 78. So taking 2 off this gives 76
The correct options are as follows:
1. A.
A synthesis reaction is a type of reaction in which two or more reactants combine together to form only one product. Synthesis reaction always release energy in form of light and heat, therefore, they are usually exothermic reactions. In the option given in A, nitrogen and nitrogen combine together to form ammonia; this is a synthesis reaction.
2. D
A radioactive half life refers to the amount of time it will take for half of an original radioactive isotope to decay.
In the question given above, the half life of the element is 1000. Thus, in 1000 years only half of the original amount will remain. In another 1000 years only 1/4 of the original amount will remain and in another 1000 years only 1/8 of the original amount will remain. Therefore, it will take 3 half lives before 1/8 of the original sample remain.<span />
