Which of the following indicates that an exothermic reaction has occurred? temperature increases heat is absorbed salt is produced water is formed question 2(multiple choice worth 5 points) (03.05 lc) which of the following increases the concentration of oh- ions? acid base water salt question 3(multiple choice worth 5 points) (03.01 lc) what do atoms consist of? elements compounds charged and uncharged particles neutrons moving around a nucleus question 4(multiple choice worth 5 points) (03.01 lc) which two particles are present in the nucleus of an atom? electrons and neutrons electrons and molecules protons and neutrons protons and electrons question 5(multiple choice worth 5 points) (03.04 mc) there are 118 elements in the periodic table. what is a likely estimate of the number of compounds formed by these elements? 118 compounds as each compound is made of one element 236 compounds as each compound is made of two elements far greater than 118 because elements combine in various ways 59 compounds because elements pair up with each other to form all compounds question 6(multiple choice worth 5 points) (03.02 mc) which of the following elements has properties different than the rest? k na mg s question 7(multiple choice worth 5 points) (03.06 lc) what is a homogeneous mixture called when microscopically insoluble particles are suspended throughout another substance? colloid compound emulsion solution question 8(multiple choice worth 5 points) (03.06 mc) which statement is true about oxygen and rocks? both are mixtures. both are pure substances. oxygen is a mixture and a rock is a pure substance. oxygen is a pure substance and rocks are mixtures. question 9(multiple choice worth 5 points) (03.02 lc) which family in the periodic table has elements that are silvery and lustrous? alkali metals halogens noble gases nonmetals question 10(multiple choice worth 5 points) (03.04 lc) which statement is true about elements? they are finite in number. they are infinite in number. they combine to form atoms. they combine to form electrons. question 11(multiple choice worth 5 points) (03.04 lc) which of the following is a compound? co2 ne o2 p4 question 12(multiple choice worth 5 points) (02.04 lc) which of the following steps will speed up the reaction between coal and oxygen? keep the coal in a wide dish decrease the temperature of oxygen increase the temperature of coal keep the coal in a narrow test tube question 13(multiple choice worth 5 points) (03.05 mc) which statement is true about hcl? it is a salt because it increases the concentration of metallic ions. it is a salt because it is formed by the reaction of an acid and a base. it is an acid because it increases the concentration of hydroxide ions. it is an acid because it increases the concentration of hydrogen ions. question 14(multiple choice worth 5 points) (03.01 mc) two different sub-atomic particles are described below: particle y: carries a positive charge particle z: orbits the nucleus which statement is true? y is an electron and z is a proton. y is a proton and z is an electron. y is an electron and z is a neutron. y is a proton and z is a neutron. question 15(multiple choice worth 5 points) (03.01 lc) based on dalton's atomic theory, which of the following is true about all atoms of the same element? they have different masses. they have the same properties. they can be divided into molecules. they are composed of visible matter. question 16(multiple choice worth 5 points) (03.02 mc) nitrogen is to the immediate left of oxygen in the same row in the periodic table. which of the following statements compares the radius and number of protons of nitrogen and oxygen atoms? nitrogen has a smaller radius and one less proton than oxygen. nitrogen has a larger radius and one less proton than oxygen. nitrogen has a smaller radius and one more proton than oxygen. nitrogen has a larger radius and one more proton than oxygen. question 17(multiple choice worth 5 points) (03.02 mc) read the list of elements given below. be, mg, ca, sr which of the following about the elements is true? all of them are unreactive metalloids. all of them are hard and dense metals. be and mg are hard and dense metals and ca and sr are unreactive metalloids. be and mg are unreactive metalloids and ca and sr are hard and dense metals. question 18(multiple choice worth 5 points) (02.04 mc) it takes 1 minute for a certain amount of potassium phosphate (kh2po4) to dissolve in 100 grams of water at 50 °c. which of the following will most likely happen if the same sample of potassium phosphate is dissolved in 100 grams of water at 20 °c? the sample will dissolve in exactly 1 minute. the sample will dissolve in more than 1 minute