How many moles are in 2.91 × 10²² atoms of He?

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?

In the space, show a correct numerical setup for calculating the number of moles of co2 present in 11 grams of co2

Two metal blocks that have slightly different temperatures are placed next to one another. after five minutes, they both have lower but equal temperatures. according to the law of conservation of energy, what  most likelyhappened? energy was created inside the blocks.energy was destroyed inside the blocks.energy was absorbed into the blocks from outside the system.energy was transferred from the warmer block to the cooler block.