Question

for each chemical formula, classify as a pure compound, pure element, or mixture.
substance classification
$br_2(g)$ select
$nano_3(aq)$ pure compound
$nano_3(s)$ pure element
$p_4(s)$ mixture select

Explanation:

Step1: Analyze $Br_2(g)$

$Br_2$ is made of only bromine atoms, so it's a pure element.

Step2: Analyze $NaNO_3(aq)$

$NaNO_3(aq)$ is an aqueous solution of sodium nitrate. A solution is a homogeneous mixture, so it's a mixture.

Step3: Analyze $NaNO_3(s)$

$NaNO_3$ is composed of sodium, nitrogen and oxygen atoms chemically - bonded together, so it's a pure compound.

Step4: Analyze $P_4(s)$

$P_4$ is made up of only phosphorus atoms, so it's a pure element.

Answer:

$Br_2(g)$: pure element
$NaNO_3(aq)$: mixture
$NaNO_3(s)$: pure compound
$P_4(s)$: pure element