(plz anwser all questions 15 points)

question 1: check all the statements that are correct. conservation of mass means:

a: we can start a reaction with different types of elements than we have at the end of the reaction.

b: matter cannot be created

c: matter can be destroyed in a chemical reaction

d: we must start and end with the same amounts of matter

question 2: select all of the signs of a chemical reaction

a: a gas is released

b: a solid is formed

c: a temperature change happens

d: the change can be easily undone

e: the state of matter changes

f: a color change happens

1. according to the article, the chinese government has tried to control its people in all of the following ways except: question 1 options: create and spread propaganda in the media censorship of the media allowing people to create their own social media deleting people's social media posts without their permission question 2 (1 point) 2. when a government has total control over its citizens, including the media, it is a of government question 2 options: constitutional monarchy parliamentary democracy autocracy presidential democracy question 3 (1 point) according to the article, "social credit" is question 3 options: an experiment to people talk on-line a farming experiment that hurt people under mao ze dong using someone else's data from the internet, to give or take away things such as the right to buy an airline ticket a credit you get in china for having friends in real life, and not just on social media question 4 (1 point) china wants to take control over social media in which other region? question 4 options: taiwan chile japan hong kong

Phosphorous acid, h3po3(aq) , is a diprotic oxyacid that is an important compound in industry and agriculture. the values of phosphorous acid are 1.30 6.70 calculate the ph for each of the given points in the titration of 50.0 ml of 1.5 m h3po3(aq) with 1.5 m koh(aq) .

Asolution contains 225 g of sodium chloride, nacl, dissolved in enough water to make a 0.25 l of solution. what is the molarity of the solution?