Question 20 (1 point) which one is a true statement about endothermic reactions? question 20 options: a: energy is absorbed making it feel colder. b: more heat is given off than is put into the reaction. c: the reactants have more heat energy than the products. d: the reaction container always feels hot. question 21 (1 point) a solution in a dish contains 4.0 grams of salt dissolved in 100 grams of water. if 50 grams of the water evaporate, this is evidence that the solution is question 21 options: a: a compound b: not conserving mass c: element d: a mixture question 22 (1 point) what is true of this chemical equation? question 22 options: a: it is balanced because it is a chemical equation and follows the law of conservation of energy. b: it is balanced because the reactants and products both have hydrogen, carbon and oxygen. c: it is not balanced because there are more atoms on the products side than the reactants. d: it is not balanced because there are more atoms on the reactants side than the products. question 23 (1 point) what is the difference between a compound and a mixture? question 23 options: a: mixtures are chemically combined, but compounds are not. b: you cannot separate mixtures, but you can separate compounds. c: a compound is a pure substance, but a mixture is not. d: a mixture is a pure substance, but a compound is not. question 24 (1 point) in a solution of salt and water, which component is the solute? question 24 options: a: oxygen b: water c: beaker d: salt question 25 (1 point) which of these substances are molecules? 1. h2o 2. nacl 3. n2 4. o2 question 25 options: a: 1 and 2 b: none of them c: all of them d: 3 and 4 question 26 (1 point) what do these substances have in common? apple juice helium gas salt water copper wire question 26 options: a: they are composed of atoms. b: they are pure substances. c: they are composed of molecules. d: they are compounds. question 27 (1 point) these substances are all h2o2 li nacl o2 question 27 options: a: compounds b: molecules c: pure substances d: elements question 28 (1 point) if lavoisier heated 100 grams of powdered mercuric oxide to produce 93 grams of liquid mercury, how much oxygen would be released? question 28 options: a: 32 grams b: 93 grams c: 7 grams d: 16 grams question 29 (1 point) the following characteristics describe which of these terms? the substance is not uniform in appearance and each part of the mixture contains a combination of different ingredients in different ratios. question 29 options: a: homogeneous mixtures b: pure substance c: solution d: heterogeneous mixtures question 30 (1 point) when a solute is added to a solution, why does it remain homogeneous? question 30 options: a: the solute dissolves. b: the color concentrates at the bottom. c: it does not mix with water. d: it forms a answer all correctly and you get : ): d: ): d: ): d: ): d: ): d: ): d: )