What is the mass number of an atom which contains 28 protons, 28 electrons and 34 neutrons?

Chemical reactions that release energy A. will not occur. B. need catalysts to occur. C. will always explode. D. often occur spontaneously.

According to Le Chatelier's principle, which statement is true? The equilibrium constant is unchanged by temperature changes. The equilibrium constant changes with a change in temperature.

The decay curve shown below approximates the decay of phosphorus-32. what is the approximate half-life of phosphorus-32?

Which sentence describes an example of sublimation? A. Dew forms on leaves on a cold morning. B. Liquid deodorant sprayed on a person's body evaporates. C. Dry ice changes to carbon dioxide when kept in an open container. D.

The planets are divided into two groups name them

Which of these changes involved a physical change and not a chemical change?

Which of the following statements is true? Running an electric current through a magnet can create a magnetic field. Electric engines change electricity into magnetism. The strength of a magnetic field increases with distance.

valancy of x is 3 while that of y is 1. write a formula of the compounds when each of the seperaty combines with oxygen

The elements that contain electrons in an F sublevel near the highest occupied energy level are referred to as? A. Alkali metals B. Alkali earth metals C. transition metals D. inner transmission levels

A 5.91 g unknown sample analyzed by elemental analysis revealed a composition of 37.51 % C. In addition, it was determined that the sample contains 1.4830 * 1023 hydrogen atoms and 1.2966 * 1023 oxygen atoms. What is the empirical formula?