Question

the number 4.89 rounded to two significant figures is
a 4.90
b 5.0
c 5
d 4.9
e 4.8
question 12
if a 100. g sample of platinum metal has a volume of 4.67 ml, what is the density of platinum in g/cm³?
a 0.0467 g/cm³
b 21.4 g/cm³
c 467 g/cm³
d 2.14 g/cm³
e none of the above

Explanation:

Step1: Recall the density formula

Density formula is \(d=\frac{m}{V}\), where \(m\) is mass and \(V\) is volume. Given \(m = 100.g\) and \(V=4.67mL\). Since \(1mL = 1cm^{3}\), so \(V = 4.67cm^{3}\).

Step2: Substitute values into the formula

Substitute \(m = 100.g\) and \(V = 4.67cm^{3}\) into \(d=\frac{m}{V}\), we get \(d=\frac{100.g}{4.67cm^{3}}\approx21.4g/cm^{3}\) (rounded to three significant figures as \(100.\) has three significant figures and \(4.67\) has three significant figures, and for division, the result should have the same number of significant figures as the least - precise measurement).

Answer:

B. \(21.4g/cm^{3}\)