Answer:
Explanation: Circle
Solve for area
A=πr2
onversion result for two surface area units:
From unit Symbol Equals Result To unit Symbol
1 square centimeter cm2 , sq cm = 1.27 ∅ 1-centimeter circles ∅ 1 cm
Amount : 18 ∅ 1-millimeter circles (∅ 1 mm)
Equals : 0.14 square centimeters (cm2 , sq cm)
Fraction : 7/50 square centimeters (cm2 , sq cm)
Answer:We will use an acid to test whether sample contains calcium carbonate or not.
Explanation:
Calcium carbonate reacts with acids to give off carbon-dioxide gas ,water and calcium chloride. it is a salt of strong base calcium hydroxide and weak acid carbonic acid.

Evolution of carbon-dioxide on the reaction is also termed as effervescence.
If the sample contains the calcium carbonate strong effervesces will be observed and if not no effervescence will be observed.
We will use an acid to test whether sample contains calcium carbonate or not.
PUMICE<span>: An </span>igneous<span>-volcanic rock, it is a porous, brittle variety of rhyolite and is light enough to float. It is formed when magma of </span>granite<span> composition erupts at the earth's surface or intrudes the crust at shallow depths. It is used as an abrasive material in hand soaps, emery boards, etc.</span>