Which temperature do they need to perform the experiment for perovskite to conduct electric current? A: T=1980°C

B: T>1980°

C: T>_ 1980°C

D:T< 1980°C

For C it's suppose to be an less than equal sign .

Atrain travels 74 kilometers in 3 hours, and then 81 kilometers in 5 hours. what is its average speed?

Write the overall equation for the reaction for lithium battery

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?