Determine the number of significant figures in 400

Complete combustion of 7.80 g of a hydrocarbon produced 25.1 g of CO2 and 8.55 g of H2O. What is the empirical formula for the hydrocarbon? Insert subscripts as necessary

A hot air balloon, when fully inflated, contains 2,800,000 Liter of air. If each mole of air occupies 22.4 L of at a temperature of 120 Celsius, at what pressure is the air at when the balloon is fully inflated?

Using the equation 2H2+O2-->2H2O If 19 g of oxygen reacts completely, how many grams of hydrogen must react with it? Question options: 4.8 3.6 1.2 2.4

Determine the number of atoms in 1.75 ml of mercury. (the density of mercury is 13.5 g/ml.)

If a sample of oxygen occupies a volume of 2.15 L at a pressure of 58.0 kPa and a temperature of 25°C, what volume would this sample occupy at 101.3 kPa and 0°C? A) 1.13 L B) 3.44 L C) 4.10 L D) 1.35 L

What is a light-year? A. the distance light travels in one earth year B. the distance light travels from the sun to the earth C. the distance light travels in one orbit of the moon D. the time it takes light to travel across the universe

What's is a logical way that you could begin to investigate why your tire had low air pressure?

after balancing the redox equation FeCl3+Zn--->ZnCl2+Fe, what are the coefficients, in order from left to right?

Aluminum oxide, Al2O3, is used as a filler for paints and varnishes as well as in the manufacture of electrical insulators. Calculate the number of moles in 47.51 g of Al2O3.

What volume of 2.00 m must be added to 150.0 ml of 1.00 m chloroacetic acid to produce a buffer solution having a ph of 3.30?