Niobium-91 has a half-life of 680 years. After 2,040 years, how much niobium-91 will remain from a 300.0-g sample?

3 g

18.75 g

37.5 g

100.0 g

Calculate the density in g/mL of 2.0 L of gasoline that weighs 1.24 kg

Calculate the OH - concentration in each of the following solutions in which the H + concentrations are a. 3.5 * 10-8 M b. 0.0065 M

97.0 mg sample of Red 40 dye was dissolved and diluted to a final volume of 1.50 L with deionized water. What is the concentration of the Red 40 dye solution in ppm?

What is the composition of magma

Match these items. 1. H-CC-H (name) 2. cyclic compound with both saturated and unsaturated characteristics 3. CnH2n 4. reaction typical of unsaturated hydrocarbons 5. CnH2n-2 6. series name of hydrocarbons with triple bond 7. CnH2n+2 a. addition b.

According to the graph, which activity has used the largest amount of water over the past twenty years?

Tiffany leaves balloons filled with helium gas inside her car in on a sunny day when she returns to her car some some of the balloons are much larger and a few have popped explain what happened

If the pH indicator bromothymol blue was added to the nitric acid solution, it's colour would be?

Which statement describes a chemical reaction? Atoms in the products are rearranged to form new substances. Atoms in the reactants are rearranged to form new substances. Atoms in the products change into new atoms to form new substances.

The gases CO₂ (g) and NH₃ (g) can be liquefied at 20°C by compressing them to sufficiently high pressures. A student claims that NH₃ (g) can be liquefied at a lower pressure than CO₂ (g) can be liquefied.