4. Thorium-234 has a half-life of 24.1 days. What percentage of the original thorium-234 in a sample will remain after 144.6 days?

Whose proposal of quanta lead to the development of quantum theory?

A 52.9g sample of brass, which has a specific heat capacity of 0.375·J·g-1°C-1, is put into a calorimeter (see sketch at right) that contains 100.0g of water. The temperature of the water starts off at 15.0°C.

Classify blood as a mixture or a pure substance. if blood is a mixture, classify it as either heterogeneous or homogeneous. if blood is a pure substance, identify it as either an element or a compound.

Some fertilizer blends contain magnesium nitrate (MgNO3). Suppose that a chemist has 1.24 liters of a 2.13 M solution of magnesium nitrate. If the chemist dilutes the solution to 1.

What effect does an opaque object have on light. Explain

Ice melting, water boiling, lighting a match, grape juice freezing. Which statement describes evidence of a chemical reaction

How do the relative concentrations of hydronium ions and hydroxide ions compare in acidic solution?

Give the name of the orange metal visable after one week

What is the rough er connected to

Two students design an experiment to see if pushing or pulling a box across the floor is more effective. The first student pushes the box across the floor a distance of 20 feet and the second student times how long it takes.