If the atomic number of an element is 15, what two facts do you already know

According to the big bang theory, after the "bang," the universe remained dark until about  300,000 yearsone billion yearsthree minutesthree billion years  later, when neutral atoms began to form.

Acceleration is a direct result of a.) balanced forces b.) unbalanced forces c.) gravity d.) velocity hurry!

Four different thermometers were used to measure the temperature of a sample of pure boiling water. the measurements are recorded in the table below. thermometer temperature reading 1 temperature reading 2 temperature reading 3 w 100.1°c 99.9°c 96.9°c x 100.4°c 102.3°c 101.4°c y 90.0°c 95.2°c 98.6°c z 90.8°c 90.6°c 90.7°c the actual boiling point of pure water is 100.0°c. what can be concluded from the data about the reliability and validity of the thermometers?