Grade 12 work sheet

የ ጎንደር ዩኒቨርሲቲ የ ሪሜዲያል ተማሪዎች ውጤት ተለቋል። 👇 http://213.55.79.200 @worksheet11 @worksheet11

ዋቻሞ ዩንቨርስቲ ሪሜዲያል ውጤት ተለቀቀ። ከታች  ባስቀመጥነው ሊንክ ተማሪዎች ገብታችሁ ውጤታችሁን ማየት ትችላላችሁ https://www.wcu.edu.et/wcuresults.aspx ለእውነተኛ እና ፈጣን መረጃ Share Share👆👆👆🙏🙏 @worksheet11 @worksheet11

የደብረ ታቦር ዩንቨርስቲ ሪሜዲያል ውጤት ተለቀቀ ከላይ ባያያዝነው ፋይል መመልከት ትችላላችሁ ( ናቹራል ሳይንስ) ለእውነተኛ እና ፈጣን መረጃ 👇👇👇👇👇👇👇 @worksheet11 @worksheet11

የደብረ ታቦር ዩንቨርስቲ ሪሜዲያል ውጤት ተለቀቀ ከላይ ባያያዝነው ፋይል መመልከት ትችላላችሁ (ሶሻል ሳይንስ) ለእውነተኛ እና ፈጣን መረጃ 👇👇👇👇👇👇👇 @worksheet11 @worksheet11

የደብረ ታቦር ዩንቨርስቲ ሪሜዲያል ውጤት ተለቀቀ ከላይ ባያያዝነው ፋይል መመልከት ትችላላችሁ (ሶሻል ሳይንስ) የደብረ ታቦር ዩንቨርስቲ ሪሜዲያል ውጤት ተለቀቀ ከላይ ባያያዝነው ፋይል መመልከት ትችላላችሁ (ናቹራል ሳይንስ) ይቀላቀሉን👇 @worksheet11 @worksheet11

Question (gr 12 unit 1) 🔴#1 Degenerative diseases are A. types of infectious diseases. B. Caused as aresult of person’s working condition C. Caused as a result of ageing D. Caused by lack of nutrients in our diet. 🔴#2  Which one of the following is a genetic disease? A. Fibrosis B. Haemophilia C. Scurvy D. Heart disease 🔴#3 From which one of the following was the first antibiotics produced? A.  bacteria B. Virus C. Protozoa D. None 🔴#4 The period when the body keeps replacing the T-cells as fast as they are destroyed by HIV is called  A. latency period B. incubation period C. window period    D. None ✅Answer __? ♻️Join us👇👇👇👇 @worksheet11 @worksheet11

🛑Structure of the Atom🛑 ➖By 1900, it was discovered that the atom was not a simple, indivisible particle, but rather it contains sub-atomic particles. ➖J.J. Thomson discovered the sub-atomic particle namely ‘electron.’ ➖J.J. Thomson was the first person who proposed a model for the structure of an atom. ➖In 1886, E. Goldstein discovered the presence of new radiations in a gas discharge and named them canal rays. ➖Another positively charged sub-atomic particle was discovered with experiments of canal rays and named it proton. 🧿Thomson’s Model of Atom ➖Thomson proposed that an atom consists of a positively charged sphere and the electrons (negative charge) are embedded in it (as shown in the image given below). ➖Further, Thomson said that the negative and positive charges are equal in magnitude. Thus, the atom as a whole is electrically neutral. 🧿Rutherford’s Model of Atom ➖E. Rutherford is popular as the ‘Father’ of nuclear physics. ➖Rutherford is largely known for his work on radioactivity and the discovery of the nucleus of an atom with the gold foil experiment (as shown in the image given below. ➖Rutherford said that in an atom, there is a positively charged center known as the nucleus. ➖Rutherford said that nearly all the mass of an atom exists in in the nucleus. ➖According to Rutherford, the electrons revolve around the nucleus in well-defined orbits. 🧿Bohr’s Model of Atom ➖Neils Bohr further extended Rutherford’s model and improved his drawbacks. ➖According to Bohr, only certain special orbits known as discrete orbits of electrons, are allowed inside the atom. ➖Bohr said that electrons do not radiate energy while revolving in discrete orbits. ➖Bohr named orbits or shells as energy levels. ➖Bohr represented these orbits or shells are by the letters K, L, M, N,… or the numbers, n = 1,2,3,4,…. 🧿Neutron ➖In 1932, J. Chadwick discovered a new sub-atomic particle i.e. neutron. ➖Neutron has no charge and a mass nearly equal to that of a proton. ➖Neutrons are present in the nucleus of all atoms, except hydrogen. 🧿Electrons Distributed in Different Orbits (Shells) ➖The maximum number of electrons that can be present in a shell is given by the formula 2n2. ➖‘n’ is the orbit number or energy level index, i.e. 1, 2, 3,…. ➖According to the given formula − First orbit i.e. K-shell will be = 2 × 12 = 2 Second orbit i.e. L-shell will be = 2 × 22 = 8 Third orbit i.e. M-shell will be = 2 × 32 = 18 Fourth orbit i.e. N-shell will be = 2 × 42 = 32 ➖Likewise, the maximum number of electrons that can be accommodated in the outermost orbit is 8. ➖Electrons are not filled in a given shell, unless the inner shells are filled. It means, the shells are filled in a step-wise manner; starting from inner shell to outer shell. 🧿Valence ➖The electrons, those are present in the outermost shell of an atom, are known as the valence electrons. ➖According to Bohr-Bury model, the outermost shell of an atom can have a maximum of 8 electrons. 🧿Atomic Number ➖The total number of protons, present in the nucleus of an atom, is known as atomic number. ➖The number of protons of an atom determines the atomic number. ➖Atomic number is denoted by ‘Z’. ➖Protons and neutrons collectively are known as nucleons. 🧿Mass Number ➖The sum of the total number of protons and neutrons, present in the nucleus of an atom, is known as mass number. 🧿Isotopes ➖The atoms of the same element, having the same atomic number but different mass numbers, is known as isotopes. E.g. Hydrogen atom has three isotopes namely protium, deuterium, and tritium. ➖The chemical properties of isotopes of an atom are similar but their physical properties are different. 🧿Isobars ➖Atoms of different elements with different atomic numbers, which have the same mass number, are known as isobars. E.g. calcium’s atomic number is 20and argon’s atomic number is 18; further, the number of electrons in these atoms is different, but the mass number of both these elements is 40. @worksheet11 @worksheet11

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የሬሚድያል ውጤት የሚለቀቀው በትምህርት ሚኒስቴር በኩል አይደለም‼️ ተቋማት ናቸው አርመው ውጤቱን ለትምህርት ሚንስቴር የሚያስተላልፉት👍 ዩንቨርሲቲዎች ውጤት ይፋ ሲያደርጉ ሼር እናደርጋለን✌️ @worksheet11 @worksheet11