Which phrase describes a compound that consists of two elements? (1) a mixture in which the elements are in a variable proportion (2) a mixture in which the elements are in a fixed proportion (3) a substance in which the elements are chemically combined in a variable proportion (4) a substance in which the elements are chemically combined in a fixed proportion

Option D

Explanation:

Compound is made of more than one type of elements that is chemically combined in a fixed proportion.

Compounds are made of more than one type of elements. The elements of the compound are hold together by chemical bonds.

Two same elements does not forms any bond in the compound so different elements are required to form a bond.

hence, the correct answer is option D

the answer is 0.42 is that is an option. this question provides no info

percent abundance for cu-63 can be shown as:

63 x + 65 (1-x) = 62.9296

65 - 62.9296 = 2 x

x = 1.035

thus, percent abundance for cu-63 is 1.035

percent abundance for cu-65 can be shown as:

63 x + 65 (1-x) = 64.9278

65 - 64.9278 = 2 x

x = 0.0361

thus, percent abundance for cu-63 is 0.0361

the mass spectrum of cu-63 showing the intense peak as, this isotope is found in nature more abundantly around 92.38 % in comparison to cu-65 which is found 62.58 % naturally