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✅Structure of Atom MCQs #Chemistry📕 #ESSLCE 1. Neutron was discovered by ————– (a) J.J Thomson (b) Chadwick (c) Rutherford (d) Priestley Ans: (b) Chadwick Solution: Chadwick (1932) discovered the neutral particles Neutron. 2. The nucleus of the atom consists of ————– (a) Protons and neutrons (b) Protons and electrons (c) Neutrons and electrons (d) Protons, neutrons and electrons Ans: (a) Protons and neutrons Solution: The nucleus of the atom consists of protons and neutrons. 3. The radius of an atomic nucleus is of the order of————– (a) 10-10 cm (b) 10-13 cm (c)10-15 cm (d) 10-8 cm Ans: (b) 10-13 cm Solution: The radius of an atomic nucleus is of the order of 10-13 cm. 4. Isotopes of an element have ————– (a) Different chemical and physical properties (b) Similar chemical and physical properties (c) Similar chemical but different physical properties (d) Similar physical but different chemical properties Ans: (c) Similar chemical but different physical properties Solution: Atoms of the same element which have the same atomic number but different mass number are called isotopes. So they have Similar chemicals but different physical properties. 5. Which of the following pairs represents isobars? (a) 3He2 and 4He2 (b) 24Mg12 and 25Mg12 (c) 40K19 and 40Ca20 (d) 40K19 and 39K19 Ans: (c) 40K19 and 40Ca20 Solution: Atoms of different elements that have the same mass number but different atomic number are called isobars. 6. The atomic orbital is ————– (a) The circular path of the electron (b) Elliptical shaped Orbit (c) Three-dimensional field around nucleus (d) The region in which there is a maximum probability of finding an electron Ans: (d) Solution: The region in which there is a maximum probability of finding an electron is called orbital. 7. Principal, Azimuthal and magnetic quantum numbers are respectively related to: (a) Size, shape and orientation (b) Shape, size and orientation (c) Size, orientation and shape (d) None of the above Ans: (a) Size, shape and orientation Solution: Principal, Azimuthal and magnetic quantum numbers are respectively related to Size, shape and orientation. 8. The electronic configuration of chromium (Z=24) is: (a) [Ne] 3s2 3p6 3d4 4s2 (b) [Ne] 3s2 3p6 3d5 4s1 (c) [Ne] 3s2 3p6 3d1 4s2 (d) [Ne] 3s2 3p6 4s2 4p4 Ans: (b) [Ne] 3s2 3p6 3d5 4s1 Solution: The electronic configuration of chromium (Z=24) is [Ne] 3s2 3p6 3d5 4s1. 9. According to Aufbau principle a new electron enters the orbitals when: (a) (n + l) is minimum (b) (n + l) is maximum (c) (n + m) is minimum (d) (n + m) is maximum Ans: (a) (n + l) is minimum Solution: According to the Aufbau principle a new electron enters the orbitals when (n + l) is minimum. So the 4s orbital filled first then the 3d orbital. 10. Which of the following is not permissible? (a) n= 4, l = 3, m= 0 (b) n= 4, l = 2, m= 1 (c) n= 4, l = 4, m= 1 (d) n= 4, l = 0, m= 0 Ans: (c) n= 4, l = 4, m= 1 Solution: The value of the Azimuthal quantum number always lies between 0 to n-1. If n=4, then l= 4 not possible.

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📌Question ️4️⃣1️⃣ ✅A rectangular garden with an area of 250 square meters is to be located next to a building and fenced on three sides, with the building acting as a fence on the fourth side. Find the dimensions of the garden that will minimize the amount of fencing required. 📝Solution👇 📚Let's assume that the length of the garden is x meters and the width is y meters. Then, the area of the garden is given by: xy = 250 📚We want to minimize the amount of fencing required, which is the perimeter of the garden. Since the building acts as a fence on one side, we only need to fence the other three sides, which have lengths x, y, and x, respectively. Therefore, the perimeter P of the garden is: P = x + y + x = 2x + y 📚Now use the area equation to express the perimeter P in terms of x only, y = 250/x Substituting this into the perimeter equation, to get: P = 2x + 250/x To minimize P, we need to find the value of x that makes the derivative of P with respect to x equal to zero: dP/dx = 2 - 250/x^2 = 0 Which simplifies to x^2-125=0 [📚Recall: the derivative of x is 1 and derivative of 1/x is -1/x^2📚] Solving for x, we get: x = 5√5, And, substituting this value of x back into the area equation, we get: y = 10√5 📚Therefore, the dimensions of the garden that will minimize the amount of fencing required are approximately 5√5, meters by 10√5, meters. ✅For any information use: 👉👉tutorialpointeth@gmail.com 📣📣 🙏HELP THE CHANNEL TO REACH TO THOSE WHO NEEDS IT🙏 🙏 Share👇👇 https://t.me/tutorialpointeth