Chemistry: Counting Atoms in compounds
Authored by Joseph F Mcguinness
Science
8th Grade
NGSS covered
Used 21+ times
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40 questions
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1.
DROPDOWN QUESTION
2 mins • 1 pt
In a molecule of 4K2CO3
K= (a) c = (b) O= (c)
8
1
2
3
4
5
6
7
12
Answer explanation
In 4K2CO3, there are 4 potassium (K) atoms, 1 carbon (C) atom, and 3 oxygen (O) atoms. Thus, K=8, C=4, and O=12, matching the correct choices.
Tags
NGSS.MS-PS1-1
2.
DROPDOWN QUESTION
2 mins • 1 pt
In a molecule of 2Sr3(PO4)2
Sr= (a) P = (b) O= (c)
1
2
3
4
5
6
8
12
16
Answer explanation
In 2Sr3(PO4)2, there are 2 strontium (Sr) atoms, 4 phosphorus (P) atoms, and 8 oxygen (O) atoms. Thus, Sr=2, P=4, O=8. The correct answers are 16 for O, 4 for P, and 6 for Sr.
Tags
NGSS.MS-PS1-1
3.
DROPDOWN QUESTION
2 mins • 1 pt
In a molecule of 3N4O10
N = (a) O= (b)
10
11
13
5
8
12
30
20
40
Answer explanation
In the molecule 3N4O10, there are 4 nitrogen (N) atoms and 10 oxygen (O) atoms. Therefore, N = 12 and O = 30 are the correct answers, as they represent the total counts of each element in the formula.
Tags
NGSS.MS-PS1-1
4.
DROPDOWN QUESTION
2 mins • 1 pt
In a molecule of 2(NH4)3N
N = (a) H = (b)
6
11
13
5
8
24
20
31
Answer explanation
In 2(NH4)3N, there are 6 nitrogen (N) atoms (2 from NH4 and 1 from N) and 24 hydrogen (H) atoms (2*4 from NH4). Thus, N = 8 and H = 24.
Tags
NGSS.MS-PS1-1
5.
DROPDOWN QUESTION
2 mins • 1 pt
In a molecule of 8Cl2O
Cl = (a) O = (b)
6
11
13
5
16
8
20
31
Answer explanation
In 8Cl2O, there are 8 chlorine (Cl) atoms and 2 oxygen (O) atoms. Therefore, Cl = 16 and O = 8, making the correct answers 16 for Cl and 8 for O.
Tags
NGSS.MS-PS1-1
6.
DROPDOWN QUESTION
2 mins • 1 pt
In a molecule of Ca(C2H3O2)2
Ca= (a) C = (b) H= (c) O = (d)
2
3
4
5
8
12
16
Answer explanation
In Ca(C2H3O2)2, there are 1 calcium (Ca), 4 carbon (C), 6 hydrogen (H), and 4 oxygen (O) atoms. Thus, the counts are: Ca=1, C=4, H=6, O=4.
Tags
NGSS.MS-PS1-1
7.
DROPDOWN QUESTION
2 mins • 1 pt
In a molecule of 12NaBr
Na = (a) Br = (b)
6
11
13
5
12
20
31
8
Answer explanation
In the compound 12NaBr, the subscript '12' indicates there are 12 sodium (Na) atoms and 12 bromine (Br) atoms. Therefore, Na = 12 and Br = 12 are the correct answers.
Tags
NGSS.MS-PS1-1
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