Grade 10_Chemistry_Endterm of term 2 Exam(assessment)

[00:00:00]All right, welcome back. Today, we are discussing term two end term assessment.

[00:00:08]That is chemistry brought to you by teacher Ayubu Miti. Remember, this is Kenya certificate of basic education for senior school assessment.

[00:00:19]The exam is term two end term assessment uh grade 10 chemistry answers.

[00:00:28]So, for question one, that's section A.

[00:00:30]Section A carries uh 13 marks.

[00:00:35]Mhm. In Anklang senior school laboratory, learners observed a certain atomic model.

[00:00:43]Name the parts and labeled uh plus.

[00:00:49]The plus part uh should be uh proton.

[00:00:53]So, protons are a positively charged particle.

[00:00:57]Positively charged particle. That one is proton, not nucleus. It is proton.

[00:01:04]Identify the particle labeled E.

[00:01:07]That one is electron.

[00:01:10]Question two.

[00:01:12]State one feature of Rutherford's atomic model.

[00:01:17]Rutherford states that the atom consists of tiny dense positively charged central core called the nucleus around which negatively charged electrons revolve in a in its orbits leaving most of the atom as empty space.

[00:01:37][music] Question D. Define the term isotopes.

[00:01:50]Isotopes, these are atoms of the same elements with the same atomic number.

[00:01:55]Uh same atomic number, meaning they have the same number of protons, but in different mass number due to difference in neutrons.

[00:02:06]So, they have same atomic number because of the same protons, but different mass number because of difference in neutrons.

[00:02:16]State one use of isotope.

[00:02:19]One, used in medicine for cancer treatments or radiotherapy.

[00:02:27]Uh or as carbon tracers to determine the age of fossils. That is carbon-14 dating. Carbon-14 in atomic number one earlier.

[00:02:40]The age of fossils.

[00:02:45]Question two.

[00:02:47]In grade 10 learners in grade 10 learners from Chewyet Senior School tested the pH of five substances.

[00:02:58]A, B, C, D, and E.

[00:03:01]Which of the substance here is [music] likely to be sodium hydroxide?

[00:03:08]Sodium hydroxide in a vacuum B because of [music] pH 14.

[00:03:15]Pure water is indeed because pure water is neutral, pH of seven.

[00:03:20]Tomato juice is E um because it is a weak acid of pH four.

[00:03:27]Then hydrochloric acid is uh strong acid, that is C.

[00:03:33]So, it has a pH of one, meaning that one is a a strong acid.

[00:03:40]So, allow me to proceed to the next question.

[00:03:49]B. State one product of acid plus metal reaction.

[00:03:53]So, acid plus metal reaction to not better salt plus hydrogen gas.

[00:04:07]So, hydrogen gas is the end product.

[00:04:10]Salt and hydrogen gas is the end product of metal reacting with the acid.

[00:04:36]Distinguishing between strong and the weak acid.

[00:04:40]Strong acids fully ionizes in aqueous solutions to yield a high concentration of hydrogen ions.

[00:04:50]Whereas weak acid only partially ionizes in aqueous solutions thus releasing a low concentration of hydrogen ions.

[00:05:14]Question three.

[00:05:15]The ingredients given below represent parts of the periodic table.

[00:05:21]What is the name is given to the family of elements to which A and C belong?

[00:05:31]A and C.

[00:05:34]So, A and C belong to a group of family known as noble gases.

[00:05:42]Do you remember examples of noble gases?

[00:05:46]Yes. Noble gases these are also known as inert or rare gases.

[00:05:52]They are unreactive.

[00:05:55]The elements in nature noble gases.

[00:05:58]Examples we have argon, krypton, xenon, and etc. Roman two, write the chemical formula of the sulfates of elements in D.

[00:06:24]Which letter represent the most reactive?

[00:06:29]A, metal, Y, most electropositive down group one.

[00:06:38]B, nonny metal, E, most electronegative top of group seven.

[00:06:50]Roman four, select one element that belongs to period four.

[00:06:57]That is D.

[00:06:58]Or I L M. [music] Five, explain why the ionic radius of element E is bigger than the atomic radius.

[00:07:18]Element E belongs to group seven and reacts by gaining an electron to form a negative ion.

[00:07:25]The incoming electron increases the electron electron to electron repulsion in the outermost energy level, thus causing the electron cloud to expand while the nuclear charge remains constant.

[00:07:48]>> [snorts] >> Six.

[00:07:50]The electron configuration of an divalent anion of element N is 2 8 8.

[00:07:58]Indicate the position of element N on the periodic table drawn above.

[00:08:10]Element N has an atomic of 16.

[00:08:14]That is 2 8 8.

[00:08:19]Together with 18 electrons.

[00:08:24]Its configuration is 2 8 6.

[00:08:30]Period 3, group 6.

[00:08:33]It belongs directly below element H in the grid.

[00:08:44]Seven. How do the atomic radii of I and C compare?

[00:08:50]While explaining your answer.

[00:08:53]The atomic radius of I is bigger than that of C.

[00:08:58]Element I has fewer energy levels, that is three levels. Configuration of 2 8 3.

[00:09:05]Compared to C, which has three levels but a much higher nuclear charge, pulling electrons closer.

[00:09:15]Wait.

[00:09:16]Looking at the grid, I is in period 3, group 3. C is in period 3, group 8.

[00:09:23]Across the period, atomic radius decreases due to an increase in nuclear charge, which pulls the outermost electrons more strongly towards anyone's. Sorry, not two ones, but any ones.

[00:09:39]Therefore, the atomic radii of I is bigger than that of C.

[00:09:53]Eight, explain the trend in the first ionization energies of the elements J, I, and L.

[00:10:05]Answers, identify the bond in a sodium chloride.

[00:10:10]The answer is ionic [music] bond or electrovalent bond.

[00:10:17]Name one property of ionic bonds or ionic compounds.

[00:10:23]They have high melting and in boiling points.

[00:10:28]Two, they conduct electricity in molten states or aqueous solution.

[00:10:36]Distinguish ionic and covalent bond.

[00:10:39]An ionic bond is formed via the complete transfer of electrons from a metallic atom to a non-metallic atom. Whereas, a covalent bond is formed via the mutual sharing of valences electrons between non-metal and atoms.

[00:10:57]Between non-metal atoms.

[00:11:01]So, ionic is between metal and non-metal. Covalent between non-metals.

[00:11:09]State one use of metallic bonding material.

[00:11:15]Used in making electric cables stroke wires.

[00:11:20]Two, construction material like beams and iron sheets due to high malleability and its strength.

[00:11:37]>> As known as neutralization reaction.

[00:11:43]Identify two types of salts.

[00:11:45]Normal salts.

[00:11:47]We have acid salts.

[00:11:50]We have basic salts and double salts.

[00:11:55]Normal salts, acid salts, basic salts and all double salts. Those are the examples of salts [music] or types of salts.

[00:12:05]State one use of salts.

[00:12:07]Food preservation and the seasoning agents.

[00:12:11]Number two, you can talk about manufacture of making powder.

[00:12:15]Also known as sodium bicarbonate.

[00:12:18]Those are the two uses of salts.

[00:12:23]But there are so many other uses of salts, but these are to clean and the solid. You have decided to name one and the second one for conditioning case of the solid is the solid manufacturing of making powder.

[00:12:37]Number six, at Kakamega senior school, learners tested hydrochloric acid with metals.

[00:12:45]Identify the gas produced.

[00:12:49]That is hydrogen gas. So acid react with metal to get gas salt and hydrogen gas.

[00:12:57]Describe two properties of acids. One, they have a sour taste. Two, they [music] turn blue litmus paper red.

[00:13:07]Write two reactions of acid with metal oxide.

[00:13:12]So metal oxide react with acid to get salts and water.

[00:13:20]Then with carbonates to get salts, water, and carbon four oxide.

[00:13:27]All together.

[00:13:30]State one [music] use of acid in industry.

[00:13:34]Used in the manufacture of fertilizers and used sulfuric acid to make ammonium sulfate.

[00:13:42]Also acid used [music] in car batteries and ETC. Question 7A. What is the order of reactivity of the metals?

[00:13:55]Table with P, Q, R.

[00:13:58]So, uh order of reactivity to the highest in reactive to the lowest in reactivity.

[00:14:08]So, highest reactive or high reactive to the P, then R, Q.

[00:14:14]P reacts with them both the water and the acid. R reacts with the acid only and the Q reacts with the neither.

[00:14:22]So, it is P, R, and Q.

[00:16:05]>> Mhm.