Question

1. what type of reaction is the following: $2h_2 + o_2 \

ightarrow 2h_2o$
a. combination
b. decomposition
c. single replacement
d. combustion

1. what type of reaction is the following: $zn + 2hcl \

ightarrow zncl_2 + h_2$
a. combination
b. single replacement
c. double replacement
d. combustion

1. what type of reaction is the following: $2nahco_3 \

ightarrow na_2co_3 + co_2 + h_2o$
a. decomposition
b. combination
c. single replacement
d. double replacement

1. the ph of a solution is tested, and it is found to be a basic solution. of the following choices, what could the ph have been?

a. 3
b. 5
c. 7
d. 9

1. pure water has a ph of 7. pure water ______.

a. is a base
b. could be either an acid or a base
c. is a neutral substance
d. is an acid

1. acids are found on the ph scale between which numbers?

a. 0-7
b. 7
c. 7-14
d. 19-42

1. turns litmus blue.

a. acids
b. bases
c. salts
d. all

Explanation:

Question 49

Step1: Recall reaction types

Combination: \( A + B
ightarrow AB \). Decomposition: \( AB
ightarrow A + B \). Single Replacement: \( A + BC
ightarrow AC + B \). Combustion: Usually with \( O_2 \) producing \( CO_2 \) and \( H_2O \), but here \( 2H_2 + O_2
ightarrow 2H_2O \) is \( H_2 \) and \( O_2 \) combining to \( H_2O \), so combination.

Step1: Analyze reaction

\( Zn + 2HCl
ightarrow ZnCl_2 + H_2 \): Zn replaces H in HCl, so single replacement ( \( A + BC
ightarrow AC + B \) where A=Zn, B=H, C=Cl).

Step1: Identify reaction type

\( 2NaHCO_3
ightarrow Na_2CO_3 + CO_2 + H_2O \): One compound breaks into multiple, so decomposition ( \( AB
ightarrow A + B + C \) here).

Answer:

A. Combination

Question 50