The electron configuration of an element is 1s22s2. How many valence electrons does the element have? (1 point) a 1 b 2 c 3 d 4

An alcohol thermometer makes use of alcohol's changing in order to measure temperature. as the temperature goes up, the alcohol contained in the thermometer increases in volume, filling more of the thermometer's tube.

How does a scientist the government? a. the scientist tells people in society what to do. b. the scientist determines the policies that the government spends money on. c. the scientist provides unbiased information to the government. d. the scientist makes laws based on his or her research results.

Which of the following is an indication that a substance has undergone a chemical change? a. no new product has been formed. b. the color of the substance has not changed. c. the original constitute has not changed. d. the molecular structure has changed.