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WorksheetsLamp/Gonzalo Chavira- STAAR RELEASED TEST 2015
Total questions: 7
Worksheet time: 2hrs 45mins
Coal contains carbon and other elements. Carbon dioxide forms when coal burns in the presence of oxygen. Which of these is the best evidence that a chemical reaction occurs when coal burns?
The shape of the coal changes.
Oxygen is present.
A new substance is produced.
Coal is made up of more than one element.
The atoms of a certain element each contain 11 protons and 1 valence electron. Which statement correctly identifies this element and describes its chemical reactivity?
The element is sodium, and it is highly reactive
The element is fluorine, and it is not very reactive.
The element is sodium, and it is not very reactive.
The element is fluorine, and it is highly reactive.
Substance 1
Substance 2
Substance 3
Substance 4
An atom of a certain element has 36 protons, 36 electrons, and a mass number of 84. At room temperature this element is a very stable gas. How many neutrons are in this atom?
47
41
48
43
All the following reactions are correctly balanced except —
2C H + 5O ⎯ →⎯ 4CO + 2H O
4Fe + 3O ⎯ →⎯ 2Fe O 2 2 3
NaHCO ⎯ →⎯ Na CO + + H O CO
2CH OH + 3O ⎯ →⎯ 2CO + 4H O
Which of these elements is in this group?
Lithium
Strontium
Aluminum
Silicon
Which of these formulas contain equal numbers of nitrogen atoms?
Formulas I and III
Formulas I and IV
Formulas II and III
Formulas I, II, and V
