Mendeleev’s table of elements was better accepted than those of other scientists at the time . moseley went a step further in suggesting that the elements be arranged according

Mendeleev’s table of elements was better accepted than those of other scientists at the time because it predicted correctly the properties of elements that had not yet been discovered. Moseley went a step further in suggesting that the elements be arranged according to atomic number.

Explanation:

Mendeleev arranged the elements in order of increasing its atomic mass and then placed the elements with similar properties below each other.  In his table, He grouped the elements according to their properties. So, this corrected some wrong atomic masses.

Also, He left some blank spaces in the table.  

Mendeleev assumed that the blank spaces represented elements that had not yet been discovered and predicted the chemical and physical properties of five of the missing elements. Then, 3 of these elements were discovered in the next 15 years, and their properties closely matched Mendeleev's predictions. So, chemists approved Mendeleev's Periodic Table.Physicist Henry Moseley studied the x-ray spectrum of 12 elements, 10 of which occupied series places in the periodic table.  Moseley proofed that “there is in the atom a fundamental quantity, which increases by regular steps as we pass from one element to the next.” And this quantity referred to as atomic number in 1920 by Ernest Rutherford.

Adozen is 1221/12 = 1.751.75 x 12 = 21therefore, 1.75 is the answer.