The balanced equation is 2C2H6 + 7O2 → 4CO2 + 6H2O. Therefore, 4 moles of C2H6 require 14 moles of O2, which means 7 moles of O2 for 2 moles of C2H6.

The number of relations on a set with n elements is 2^(n^2). For n = 3, it is 2^(3^2) = 2^9 = 512.

There are 3600 seconds in an hour (60 seconds x 60 minutes).

The measurement 0.004560 has 4 significant figures (the leading zeros are not counted).

Leading zeros do not count, but the trailing zero after the decimal does. Therefore, 0.05060 has 4 significant figures.

The significant figures are 5, 0, and the trailing zero counts, totaling 3.

The number 0.004560 has 4 significant figures (the leading zeros are not counted).

Leading zeros do not count as significant figures. The significant figures in 0.00456 are 4, 5, and 6, which totals to 3 significant figures.

The significant figures are 7, 8, 9, and the trailing zero counts.

The trailing zero after the decimal point counts as a significant figure.

All non-zero digits are significant, so 1002 has 4 significant figures.

5000 has 1 significant figure unless specified otherwise (e.g., 5000. has 4 significant figures).

5000 has 1 significant figure unless specified with a decimal point (e.g., 5000. has 4).

The number of subsets of a set with n elements is 2^n. Here, n = 4, so 2^4 = 16.

The number of subsets of a set with n elements is 2^n. Here, n = 6, so the number of subsets is 2^6 = 64.

The number of subsets of a set with n elements is 2^n. Here, n = 6, so 2^6 = 64.

The number of subsets of a set with n elements is 2^n. Here, n = 4, so the number of subsets is 2^4 = 16.

The number of subsets of a set with n elements is 2^n. Here, n = 6, so the number of subsets is 2^6 = 64.

The number of subsets of a set with n elements is 2^n. Here, n = 5, so 2^5 = 32.

The number of subsets of a set with n elements is given by 2^n. Here, n = 4, so the number of subsets is 2^4 = 16.

The number of subsets of a set with n elements is 2^n. Here, n = 3, so the number of subsets is 2^3 = 8.

The number of subsets of a set with n elements is 2^n. Here, n=4, so the number of subsets is 2^4 = 16.

The number of subsets of a set with n elements is 2^n. Here, n = 3, so the number of subsets is 2^3 = 8.

The only subset that does not contain y is {∅} and {x}. Total = 2.

The number of ways = 5C2 * 4C2 = 10 * 6 = 60.

The number of ways is C(6,2) * C(4,2) = 15 * 6 = 90.

The number of ways to choose 3 books from 7 is 7C3 = 7! / (3! * 4!) = 35.

The number of ways is C(8,3) = 56.

The number of ways to choose 3 from 5 is given by 5C3 = 10.

The number of ways is C(11, 3) = 165.