Radioactive decay of 40K atoms in an igneous rock has resulted in a ratio of 25 percent 40K atoms to 75 percent. 40Ar and 40Ca atoms. How many years old is this rock?

How does a circuit breaker protect a refrigerator? a. when the current is too high, a metal strip in the fuse melts and opens the circuit. b. when the resistance is too high , a re-settable which opens a circuit c. when the current is too high , a re-settable switch opens the circuit d. when the resistance is too high a metal strip in the fuse melts and opens the circuit

Would it be correct to say the doppler effect is the apparent change in the speed of a wave due to the motion of the source? be sure to fully explain your position using at least 3 complete content related sentences.

According to the image below, which season is about to begin in the southern hemisphere? a. summer b. autumn c. winter d. spring