Determine whether there exists a short exact sequence 0→Z4→Z8⊕Z2→Z4→0. More generally, determine which abelian groups A fit into a short exact sequence 0→Zpm→A→Zpn→0 with p prime. What about the case of short exact sequences 0→Z→A→Zn→0?

Which of the following statements is false regarding aromaticity? a. the compound must be cyclic b. the compound must be fully conjugated c. the compound must be planar d. the number of electrons in the pi system must satisfy the hückel 4n+2 rule e. the compound must have a neutral charge

About 3% of the water on earth is freshest. only about 40% of that freshwater is available for human use. why is so much freshwater unavailable for human use?

Which sample at stp has the same number of atoms as 18 liters of ne at stp