Why firefighters don't use fire extinguishers?

What neutral atom is isoelectronic to mn+4

Which substances have the lowest melting points: ionic covalent, or metallic

Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture