26. Why did Mendeleev leave spaces in his periodic

table?

Why do clouds form before it rains?

What percentage of strontium-90 remains in a sample after three half-lives have passed? 12.5% 15% 25% 60%?

State 3 evidences that the particles of substances are in continuous motion

metal weighing 6.98 g was heated to 91.29 °C and then put it into 114.84 mL of water (initially at 24.37 °C). The metal and water were allowed to come to an equilibrium temperature, determined to be 33.54 °C.

If a substans is a mineral, how could you identify what type of mineral it is?

What happens when francium and nitrogen are mixed

Which type of chemical reaction occurs in 2KClO3 Right arrow. 2KCl + 3O2

An electrochemical cell is constructed using two half-cells: Al (s) in Al (NO2) 3 (aq) and Cu (s) in Cu (NO3) 2 (aq). The two half cells are connected by a KNO3 salt bridge and two copper wires from the electrodes to a voltmeter.

7. If you fill a balloon with 5.2 moles of gas and it creates a balloon with a volume of 23.5 liters, how many moles are in a balloon at the same temperature and pressure that has a volume of 14.9 liters

Which compound is formed from its elements by an exothermic reaction at 298 K and 101.3 kPa?