Question

Which two of the choices below MUST be applied in order to work with the law of conservation of mass? (Select two.)(2 points)
Responses

All compounds must have a coefficient greater than 1 in front of them before conservation can be supported.
All compounds must have a coefficient greater than 1 in front of them before conservation can be supported.

The masses must be in a closed system.
The masses must be in a closed system.

The experimenter should change subscripts until the equation is balanced.
The experimenter should change subscripts until the equation is balanced.

The equation has to be balanced.
The equation has to be balanced.
Question 2
When the alkali metal rubidium reacts with water, it forms rubidium hydroxide and hydrogen gas. Use what you've learned about balancing equations to select the correct coefficients to represent the law of conservation of mass for the reaction below.

rubidium + water → rubidium hydroxide + hydrogen

Rb (s) + H2O (l) → RbOH (aq) +H2 (g)

(4 points)

Rb (s) +

H2O (l)
→

RbOH (aq) +

H2 (g)
Question 3
Using the chemical equations above as models, connect the part of the chemical equation with its "meaning". Select only one solution per blank. (6 points)
Put responses in the correct response input area to answer the question. Select a response, navigate to the desired input area and insert the response. Responses can be selected and inserted using the space bar, enter key, left mouse button or touchpad. Responses can also be moved by dragging with a mouse.
a sign a chemical reaction has occurred, gas bubbles form of this type
Press enter key to drop response here.
the coefficients tell you this
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one of the products that remains dissolved in water
Press enter key to drop response here.
the reactant is in solid form when it enters the reaction
Press enter key to drop response here.
the subscripts tell you this
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"yields" or "reacts to form"
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Answer 1

Question 1 — Select two (must be applied):
- The masses must be in a closed system.
- The equation has to be balanced.

Question 2 — Balanced coefficients:
2 Rb (s) + 2 H2O (l) → 2 RbOH (aq) + H2 (g)

Question 3 — Matches:
- "a sign a chemical reaction has occurred, gas bubbles form of this type" → H2 (g)
- "the coefficients tell you this" → the relative number (amounts) of molecules or moles of each substance
- "one of the products that remains dissolved in water" → RbOH (aq)
- "the reactant is in solid form when it enters the reaction" → Rb (s)
- "the subscripts tell you this" → how many atoms of each element are in a molecule
- "'yields' or 'reacts to form'" → the arrow (→)