Which best describes the act of using senses or tools to gather information?

Exit what is the density of an object having a mass of 5.0 g and a volume of 45.0 cm3?

When did stem cell research become known ? who discovered stem cell? what experiments or studies have been conducted so far?

2ki + pb(no3)2 → 2kno3 + pbi2 determine how many moles of kno3 are created if 0.03 moles of ki are completely consumed.