Question 1;
The answer is carbon dioxide and water. A product is what is formed by a chemical reaction. Reactants are the elements or compounds at the start of the reaction A chemical reaction mostly involves the exchange of atoms such as in this case where its shown in the equation below
CH4 + 2O2 - CO2 + 2H2O
Question 2;
The answer is Energy is absorbed making it feel colder. In an endothermic reaction, the enthalpy of the products is higher than that of the products, hence the enthalpy change is positive. This means that the chemical reaction absorbs heat from the environment.
Question 3;
The answer is a precipitate. A precipitate is formed when the one or mo0re of the products in the chemical reaction is insoluble and mostly settles down to the bottom of the reaction container of suspends in the solution. Precipitation is used as a significant indicator in particular chemical reactions.
Question 4;
The answer is Electrons are shared in a covalent bond. The covalent bond between two atoms allows the atoms to share pairs of electrons to reach a stable electron configuration in their valence orbital. In an ionic bond, one atom (mostly a metal) donates its electron to the other atom (mostly a halogen) so both have stable electron configurations.
Question 5;
The answer is 2. This is shown in the chemical formula of a water molecule (H2O). The subscript shows the number of hydrogen atoms in one water molecule. This occurs when an oxygen atom forms covalent bonds with two hydrogen atoms so it shares a pair of electrons with each hydrogen to reach stable electron configuration in their valence orbitals.
Question 6;
The answer is 4. The number in front of the molecule means there are 4 molecules of Sodium Chloride. There are no subscripts within the molecule meaning there is one (1) atom of Na and one (1) atom of Cl in the molecule. Therefore, there are four (4) atoms of sodium and four (4) atoms of chlorine in four (4) molecules of sodium chloride.
Question 7;
The answer is the law of conservation of mass. Law of conservation stipulates that energy and matter cannot be destroyed or created. This is the first law of thermodynamics that states that it can only be transformed from one form to another. In the reaction, since the number of atoms is conserved, the law of conservation (of matter in this case) has been observed.
Question 8;
The answer is 5. As stated in the previous question, chemical reactions observe the law of conservation stipulated in the first law of thermodynamics. Matter and energy cannot be created or destroyed but can only be transformed from one form to another. Chemical reactions only involve the exchange of atoms. Only in nuclear reactions that elements are transformed.
Question 9;
The answer is 3. Balancing the equation ensures that the law of conservation is observed. Since matter cannot be destroyed or created in a chemical reaction, the number of atoms of an element in the products and reactant must be the same. Therefore putting three (3) balances the equation since the number of hydrogens (H) in the products balances with the six (6) in the HCl in the reactants. The three (3) will also balance the number of oxygen atoms between the products and reactants.
Question 10;
The answer is oxygen. An element is a substance that is composed of purely one type of atoms. Oxygen is only composed of oxygen atoms while the rest are mixtures of atoms from different elements (hence are compounds).
