How can one tell how much of each reactant will be used in a reaction?

If i had 2 m naoh solution, what does the 2 m stand for? 2 molar, but 2 of a solute in 1

What causes the appearance of lines in a emission spectrum

The table below shows the freezing points of four substances. substance freezing point (°c) benzene 5.5 water 0 butane –138 nitrogen –210 the substances are placed in separate containers at room temperature, and each container is gradually cooled. which of these substances will solidify before the temperature reaches 0°c? benzene water butane nitrogen