Answered

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Question 4 of 10
Which of the following reactions shows a physical change?

A. [tex]\[NaCl (s) \rightarrow NaCl (aq)\][/tex]
B. [tex]\[2 CH_3OH (\ell) + 3 O_2 (g) \rightarrow 2 CO_2 (g) + 4 H_2O (\ell)\][/tex]
C. [tex]\[2 AgNO_3 (aq) + CaBr_2 (aq) \rightarrow 2 AgBr (s) + Ca \left( NO_3 \right)_2 (aq)\][/tex]
D. [tex]\[H_2 (g) + O_2 (g) \rightarrow H_2O (\ell)\][/tex]

Sagot :

GinnyAnswer
To determine which reaction shows a physical change, let's analyze each option.

A. [tex]\( \text{NaCl (s)} \rightarrow \text{NaCl (aq)} \)[/tex]

In this reaction, solid sodium chloride (NaCl) is dissolved in water to form an aqueous solution of NaCl. The dissolution process involves the separation of NaCl into its constituent ions, [tex]\( \text{Na}^+ \)[/tex] and [tex]\( \text{Cl}^- \)[/tex], in water. Importantly, there is no alteration of the chemical structure of NaCl; only its physical state changes from solid to aqueous. This represents a physical change.

B. [tex]\( 2 \text{CH}_3\text{OH} (\ell) + 3 \text{O}_2 (g) \rightarrow 2 \text{CO}_2 (g) + 4 \text{H}_2\text{O} (\Lambda) \)[/tex]

This equation describes the combustion of methanol ([tex]\( \text{CH}_3\text{OH} \)[/tex]) in the presence of oxygen ([tex]\( \text{O}_2 \)[/tex]), resulting in the formation of carbon dioxide ([tex]\( \text{CO}_2 \)[/tex]) and water ([tex]\( \text{H}_2\text{O} \)[/tex]). New products are formed as a result of this process, indicating a chemical change rather than a physical change.

C. [tex]\( 2 \text{AgNO}_3 (aq) + \text{CaBr}_2 (aq) \rightarrow 2 \text{AgBr} (s) + \text{Ca(NO}_3)_2 (aq) \)[/tex]

This reaction describes a precipitation reaction where aqueous solutions of silver nitrate ([tex]\( \text{AgNO}_3 \)[/tex]) and calcium bromide ([tex]\( \text{CaBr}_2 \)[/tex]) react to produce solid silver bromide ([tex]\( \text{AgBr} \)[/tex]) and aqueous calcium nitrate ([tex]\( \text{Ca}(\text{NO}_3)_2 \)[/tex]). The formation of new substances (silver bromide and calcium nitrate) indicates a chemical change.

D. [tex]\( \text{H}_2 (g) + \text{O}_2 (g) \rightarrow \text{H}_2\text{O} (M) \)[/tex]

This equation represents the reaction between hydrogen gas ([tex]\( \text{H}_2 \)[/tex]) and oxygen gas ([tex]\( \text{O}_2 \)[/tex]) to form water ([tex]\( \text{H}_2\text{O} \)[/tex]). The formation of water from hydrogen and oxygen gases is a chemical change.

Given this analysis, we can see that option A ([tex]\( \text{NaCl (s)} \rightarrow \text{NaCl (aq)} \)[/tex]) is the only reaction that represents a physical change since it involves a dissolution process without the formation of any new substances.

Thus, the correct answer is:

1.
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