Question

12 multiple choice 1 point
how many \things\ are in one mole?
1 gram
1 carbon atom
6023
6.022*10^23
clear my selection
13 multiple choice 1 point
what is the mass in grams of 0.172 moles of nahco₃?
14.0 g
4.4 grams
14.4 grams
44.4 grams
clear my selection
14 multiple choice 1 point
how many different types of atoms are present in the following chemical equation?
al₂o₃ → al + o₂

Explanation:

Question 12

The mole is a unit in chemistry representing \(6.022\times10^{23}\) entities (atoms, molecules, etc.). 1 gram is a mass unit, 1 carbon atom is a single atom, and 6023 is incorrect. So the correct option is the one with \(6.022\times10^{23}\).

Step1: Calculate molar mass of \(\ce{NaHCO3}\)

Molar mass of \(\ce{Na}\) = \(23\) g/mol, \(\ce{H}\) = \(1\) g/mol, \(\ce{C}\) = \(12\) g/mol, \(\ce{O}\) = \(16\) g/mol.
Molar mass \(M = 23 + 1 + 12 + (3\times16)\) = \(23 + 1 + 12 + 48\) = \(84\) g/mol.

Step2: Use \(m = n\times M\)

Given \(n = 0.172\) mol, \(M = 84\) g/mol.
\(m = 0.172\times84\) = \(14.448\approx14.4\) g.

In the equation \(\ce{Al2O3 -> Al + O2}\), the atoms present are Aluminum (\(\ce{Al}\)) and Oxygen (\(\ce{O}\)). So there are 2 different types of atoms. (If options include 2, that's the answer. Since the option shown is 4, but that's incorrect. Wait, the equation has Al and O, so 2 types. But based on the visible option (4), maybe a typo, but following the equation: Al and O are two atoms. So the correct count is 2, but if options have 2, that's it. If the visible option is 4, maybe the user's image cut off, but from the equation, it's 2.)

Answer:

D. \(6.022^{*}10^{23}\) (assuming D is the identifier for this option, adjust identifier if needed)

Question 13