Answer:
neon 21 ang sagot diyan
Explanation:
iyan ang sagot ko its a frank hindi yan ang sagot ko
HISTORICAL INTRODUCTION.1<span> EVER since the establishment of the atomic theory by Dalton and Berzelius it was felt among chemists that there must be some relation between the atomic weights of the different elements and their properties. It was recognized very early that there exist groups of elements possessing related chemical and physical properties, and one of the earliest attempts to bring out this point is due to Dobereiner. In 1829 he tried to show that “many elements may be arranged in groups ()f three, in each of which the middle element has an atomic weight equal or approximately equal to the mean of the atomic weights of the two extremes.” As illustrations of this method of arrangement may be mentioned the following groups: Li, Na, K; Ca,Sr,</span>
Answer: (3) decomposition and melting
Explanation: Chemical change is one in which chemical composition of substance changes.
Physical change is one in which chemical composition of substance do not change.
Freezing is a process in which a liquid changes into solid phase when allowed to cool. Thus it is a physical change.
Melting : It is process in which a solid changes into liquid phase by providing heat. Thus it is a physical change.
Vaporization : It is process in which liquid changes into gaseous phase by providing heat. Thus it is a physical change.
Decomposition is a chemical reaction in which one substance decomposes to form two or more than two products. Thus the chemical composition change, and hence is a chemical change.
Combustion is a reaction in which a substance combines with oxygen gas to produce carbon dioxide, water and a lot of heat. Thus the chemical composition change, and hence is a chemical change.
Answer:
yeast sorry it took so long
Explanation:
