A scientist designs some experiments to record how various substances change. She then reviewed her results. Which of the investigations listed below is an example of how the substance changed chemically? 1. Hydrochloric acid is stored inside plastic containers.
2. Sodium metal reacts violently and explodes with water.
3. After heating aluminum in a crucible, it began melting at 1200 degrees F
4. Grinding Copper sulfate allowed it to be dissolved much quicker.

If 21.2 kcals of energy is released by this reaction, how many kj does the reaction release? (1 cal 4.184 j)

Which is an example of gaining a static charge by conduction? a) rubbing a balloon against your hair. b) shuffling your shoes across a carpet. c) bringing a charged rod near an electroscope. d) touching your car on a cold day and getting a shock.

Alinearly polarized electromagnetic wave has an average intensity of 196 w/m^2. this wave is directed towards two ideal polarizers (in real polarizers, transmission is also effected by reflection and absorption). polarizer a is oriented with its transmission axis at an angle of θ_1=20.8∘ with the incident electric field. polarizer b has its axis at an angle of θ_2=63.0∘ with the incident electric field. what is the average intensity of the wave after it passes through polarizer a? what is the average intensity of the wave after it passes through polarizer b? suppose that the two polarizers a and b are interchanged. what would the average intensity be after passing through both polarizers?