Chemistry group 33

Barsiisonni baadiyyaa utubaa biyyaa fi ibsaa dhalootaati. Ofii haala ulfaataa fi rakkisaa keessa darbanii dhaloota boruu bocuuf of kennan. Gootummaan isaanii waraana irratti utuu hin taane, daree barnootaa keessatti beekumsa qooduu irratti mul'ata. Haala mijataa hintaane Hanqina meeshaa barnootaa kan akka kitaabolee fi Infiraastiraakcherii, ga’aa utuu hin qabaatin, mala ofiitiin uumanii barsiisuun kutannoo isaanii agarsiisu. Daa'imman harka qalleeyyii akka ijoollee ofiitti kunuunsuun, abdii fi egeree gaarii akka qabaatan onnachiisu. Barsiisonni kunniin kaffaltii xiqqoodhaan, garuu jaalala guddaan hojjetu. Aarsaan isaan biyyaaf kaffalan gatii guddaa kan qabuu fi seenaan yoomiyyuu kan isaan hin irraanfannedha. Mee isiniis jaalalaa fi kabaja barsiisota keessaniif, keessattuu gootota barsiisota baadiyyaaf qabdan, bakkaa yaadaa armaan gadii irratti ibsaa. Barsiisaa keessan isa kam yaadattu? @chemistry_group33

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Kardii badhaasa namoota 30 warra add godheef 1ffa kardii qarshii 15 2ff kardii qarshii 10 3ff kardii qarshii 5

Read from above theory and answer the following questions 1. Which of the following postulates of the Dalton's atomic theory is disproved by the Modern atomic theory? A. Elements are made up of small particles called atoms. B. Atoms combine in small whole numbers to form compounds. C. All atoms of masses and size 2. Which of the following is NOT the postulate of the modern atomic theory? Atoms A. Are indivisible and indestructible B. Are the smallest particles of elements C. different element have different chemical properties D. the same element have identical chemical properties 3. One of the following statements is accepted by both Dalton's and modern atomic theories. Which one is it? A. An atom can be further subdivided into electrons, protons and neutrons B. Atoms of the same element may not be exactly alike C. Atoms of a given element are identical in mass D. All elements are made up of very small particles called atoms 4. Which of the following states the law of definite proportions? A. The total mass in the universe is always constant. B. Every compound always contains the same elements in the same proportions by weight. C. Chemical compounds are formed when atoms combine in small whole number ratios. D. The mass of the products in a chemical reaction must be equal to the mass of the reactants 5. All of the following are the properties of cathode rays EXCEPT their A. Particle nature B. Negative charge C. Independence on the cathode material D. Motion is not in a straight line. 6. Which of the following is NOT true about cathode rays? A. travel in straight lines from cathode to the anode. B. contain particles, which are negatively charged. C. are common constituents of all matter and their m/e is constant for all gases. D. contain particles, which are positively charged. 7. The existence of neutrons was discovered by A. Joseph John Thomson B. James Chadwick C. Robert Milikan D. Ernest Rutherford 8. If a chemical symbol of iodine is given by 127 53I, what are the number of electrons, protons and neutrons respectively? A. 53, 53, 127 B. 53, 127, 53 C. 53, 53, 74 D. 74, 53, 53 9. How many protons, neutrons, and electrons, respectively are there in 200 80Hg? A. 120, 80, 80 B. 80, 120, 80 C. 280, 120, 80 D. 120, 280, 80 10. How many neutrons are there in the element having a 13 C chemical 6 symbol A. 6 B. 13 C. 19 D. 7 All the above entrance exam question

The electrons are arranged in sublevels according to Aufbau principle which is also known as the diagonal rule. 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 6s 6p

The basic postulates of Dalton’s Atomic Theory 1.All elements are made up of small particles called atoms. 2.Atoms are indivisible and indestructible. 3.Atoms of the same element are identical in mass 4.Atoms are neither created nor destroyed in chemical reactions. 5.Compounds are formed when atoms of more than one element combine in a small whole number ratio

Revised Announcement for Grade 12 Students Please be informed that the schedule for the 2018 E.C. Model Examination has been revised. New Exam Dates: 14/09/2018 – 18/09/2018 E.C.

For high school students

How many groups and periods are there in the modern periodic table? A. 7,18 B. 18,7 C. 7,16 D. 16,7

• Period 1 contains only 2 elements, hydrogen and helium. • Period 2 and period 3 contain 8 elements each. • Period 4 and period 5 contain 18 elements each. • Period 6, the longest period, has 32 elements. • Period 7, which is an incomplete period, contains more than 24 elements. • Period 7 element is radioactive and/or an artificial element. • Except for the first period, all periods start with an alkali metal and ends with a noble gas