A sample that weighs 107. 75 g is a mixture of 30% helium atoms and 70% krypton atoms. How many particles are present in the sample?

1) which of the following is the best example of a physical change? a) sugar dissolving in tea b) firefly glowing 2) in the combustion of ethane, what is/are the reactants? c2h6 + o2 ==> co2 + h2o a) c2h6 and o2 b) co2 and c2h6

Who determined the nature of chemical bonds?

In a ball-and-stick molecular model, what do the sticks represent?