Question

1. how many significant figures does 0.00420 g have?

options: 2, 4, 3, 1

1. in scientific notation, what does a positive exponent mean?

options: the decimal moves to the left., the decimal moves to the right., the number is negative., the number is a fraction.

Explanation:

Question 13

Step1: Recall significant figure rules

Leading zeros (zeros before non - zero digits) are not significant. Non - zero digits are significant. Trailing zeros in a decimal number (after the non - zero digits and the decimal point) are significant.
For the number \(0.00420\):

• The leading zeros (\(0.00\)) are not significant.
• The non - zero digits \(4\) and \(2\) are significant.
• The trailing zero after \(2\) (the zero in the thousandths place after the decimal) is significant because it is a trailing zero in a decimal number.

Step2: Count the significant figures

So, the significant figures are \(4\), \(2\), and \(0\) (the trailing zero). So there are 3 significant figures.

In scientific notation, a number is written as \(a\times10^{n}\), where \(1\leqslant|a|\lt10\) and \(n\) is an integer. If \(n\) is positive, for example, if we have \(5\times 10^{3}\), this is equivalent to \(5\times1000 = 5000\). To get from \(5\) to \(5000\), we move the decimal point (which is after the \(5\) in \(5.0\)) three places to the right. A positive exponent means we are multiplying by a power of \(10\) greater than \(1\), which causes the decimal to move to the right. A negative exponent would mean the decimal moves to the left. A positive exponent has nothing to do with the number being negative or a fraction.

Answer:

3

Question 14