Strontium-90 has a half-life of 29 years. In how many years will a 1 kg sample of strontium-90 decay and reduce to 0.25 kg of strontium-90?

Answer

58 years

116 years

87 years

29 years

What is the molar mass of a compound? A) The mass in grams of 1 mole of the compound B) The number of moles in a molecular formula C) The number of atoms in 1 mole of the compound D) The number of moles in 1 g of the compound

The reaction A + 2B → products has been found to have the rate law, rate = k[A][B]2. While holding the concentration of A constant, the concentration of B is tripled. Predict by what factor the rate of reaction increases

Which of the following examples illustrates a number that is correctly rounded to three significant figures? a. 109 526 g to 109 500 g b. 0.03954 g to 0.040 g c. 20.0332 g to 20,0 g d. 04.05438 g to 4,054 g e. 103.692 g to 103.7g

How do you indicate that a substance is a solid in a chemical ecuation?

Sodium has an atomic number of 11 and has a net charge of 0. When sodium combines with chlorine, it has a net charge of + 1. Why?

Which element has six energy levels? A) rubidium (Rb) B) cesium (Cs) C) potassium (K) D) sodium (Na)

What is a segment of dna that contains a single unit of information?

Is carbon monoxide covalent or ionic?

Do all organisms perform meiosis?

which one of these reactions is energy released? A all reactions B no reactions C endothermic reactions D exothermic reactions