Which substances could be decomposed by chemical reactions?

1. water
2. sugar
3. mercury
4. argon

What is the volume of 8 g CO2 at STP? The molar mass of CO2 is 44 g/mol.

Under the symbol of 2SO3 you may understand

1. 2 moles of SO3
2. 2 molecules of SO3
3. 6 moles of O2
4. 2 x 6 x 10²³ O atoms

A radioactive isotope has a half life of 10 What fraction of the original amount of the isotope remains after 30 days?

Which main energy shell can accommodate a maximum number of 8 electrons?

An element has the electron configuration of 1s²2s²2p⁶3s²3p². The number of valence electrons is

Which element – shown with its electron dot symbol – gives a compound with nitrate ion that has the formula of X(NO3)2?

Magnesium forms an ion with a charge of

Which molecules contain polar covalent bonds?

1. CO2
2. CCl4
3. F2
4. KF

Ionic bond is likely to form between the atoms of

1. C and Br
2. Ca and I
3. P and Cl
4. O and Na

Which of the following changes will shift the reaction at equilibrium to the left?

1. Increase the concentration of H2S
2. Decrease the temperature.
3. Increase the pressure.
4. Increase the concentration of H2.

Which solution contains the largest amount of glucose?

Choose the solution with the highest hydronium ion concentration.

The oxidation number of Mn in MnO ^─ ion is

In the stomach the hydrochloric acid concentration is about 1 M. How many milliliters of the gastric fluid contain 0.5 g of HCl?

The molar mass of HCl is 36.5 g/mol.

You need to prepare a sodium chloride solution with 10 % m/m If you start from 50 g of NaCl what is the mass of water needed to make the solution?

What is/are the missing reactant/s?

Which of the compounds below are amines?

Which reactants produce an ester?

Which statement is true for disaccharides?