Na2SO3” represents sodium sulfite. What does the 4 mean in the formula 4Na2SO3?

There are four atoms of sodium.
There are four atoms of sodium sulfite.
There are four molecules of sodium sulfite.
There are four elements in sodium sulfite.
PLEASE HELP I ONLY HAVE 30MIN and i have a test today and i will be happy if you help me :) and don't be putting randon words down like putting an website i an't vistit since i am on an school comtuter also this an science question

1. an experiment in your science class lists the materials needed for the lab. it is your job, as a lab partner, to measure out 25 ml of distilled water and 2.5 grams of magnesium. what lab measuring tools would you choose to measure each substance and how would you use each tool to get the correct amounts? be sure to describe the process you would follow step-by-step. (5 points) 2.which of the following is an si base unit for measuring mass? (2 points) ampere gram meter pound 3.which of the following is an si base unit for time? (2 points) decades hours minutes seconds 4.which of the following tools should a scientist use to measure an object in milligrams? (2 points) graduated cylinder pan balance tape measure thermometer 4.which of the following tools should a scientist use to measure an object in milligrams? (2 points) graduated cylinder pan balance tape measure thermometer. 5.a pencil beside a metric ruler. the ruler is scaled from 1 centimeter to 10 centimeters, with markings for millimeters between each number. one end of the pencil is beside the 0 on the ruler, and the pencil point is beside the 5. which of the following measurements is accurate but not precise? (2 points) 5 mm 5 cm 50 mm 50 cm 6. which of the following prefixes represents the largest value? (2 points) giga hector kilo milli 7. which of the following types of graphs is best for plotting the percentages of a whole value in a data set? (2 points) bar graph circle graph histogram line graph

What is bromine+calcium iodide--> calcium bromide +iodine balanced

8. how much enthalpy/heat is transferred when 0.5113gof ammonia (nh3) reacts with excess oxygen according| to the following equation: 4nh3 +502 - 4n0+ 6h20ah = -905.4j