When does the composition of a substance does not change?

Na2CO3 + CO2 + H2O → NaHCO3 1. Which of the following coefficients would correctly balance the chemical reaction shown above? A. 1,2,3,4 B. 1,1,1,2 C. 2,1,1,1 D. 2,2,3,1

How might we create the best possible solution to a problem?

The combining of hydrogen and oxygen gas into liquid water is an example of what kind of change? A. Phase B. Chemical C. Physical

Which neutral element has the following electron configuration? 1 s^2 2s^2 2 p^6 3 s^2 3 p^41s 2 2s 2 2p 6 3s 2 3p 4

A flask apparatus is composed of 3 round flasks all connected to a single tube through a stopcock in the closed position for each flask. The first flask contains 1.15 L He at 207 torr. The second flask contains 1.15 L Ne at 0.458 atm.

The relationship between number of particles and pressure is As number of particles increases, pressure increases As number of particles increases, pressure decreases The two are not related

Consider the reaction: Al2S3 + 6 HCl → 2 AlCl3 + 3 H2S The reaction has a 29.1% yield. How many grams of Al2S3 are needed to react with 30.0 moles of HCl? a) The molar mass of Al2S3 is 150.16 grams/mole. b) The molar mass of HCl is 36.46 grams/mole.

Why is Earth's temperature just right for life? A. Earth's core is hot enough to heat Earth's surface. B. Earth's magnetic field creates suitable temperatures on Earth's surface. C. Earth's crust is warmed by heat from the sun. D.

Which of the following is an example of a chernical change? Boiling water Burning paper Dissolving sugar in water Melting gold

Part a by drawing molecular orbital diagrams for b2, c2, n2, o2, and f2, predict which of these homonuclear diatomic molecules are magnetic.