CBSE ADDA

CBSE Exam  Congruence of  Triangle Solved Questions Q. 1. Prove that Sum of Two Sides of a triangle is greater than twice the length of median drawn to third side. Given:   Δ ABC in which AD is a median. To prove:   AB + AC > 2AD. Construction:   Produce AD to E, such that AD = DE. Join EC. Proof:   In ΔADB and ΔEDC, AD = DE              (Construction) BD = BD             (D is the mid point of BC) ∠ ADB = ∠ EDC       (Vertically opposite angles) ∴ ΔADB   ≅       ΔEDC   (SAS congruence criterion) ⇒ AB = ED               (CPCT) In ΔAEC, AC + ED > AE           ( Sum of any two sides of a triangles is greater than the third side ) ∴ AC + AB > 2AD      ( AE = AD + DE = AD + AD = 2AD & ED = AB ) Q. 2.  ABC is an isosceles triangle in which AB = AC. Side BA is produced to D such that AD = AB (see the given figure). Show that ∠ BCD is a right angle. In ΔABC, AB = AC

IX CBSE - Formative Assessment-II [SET-1] Q.1. What are green revolution and white revolution? Q.2. What nutrients do the following provide: (i) Pea (ii) Linseed (iii) Vegetables (iv) pigeon pea (v) Wheat (vi) Castor (vii) Spices (viii) fruits. Q.3. Differentiate between Kharif and Rabi crops. Q.4. What is interspecific hybridization? Q.5. How does change in maturity duration of crop help the framers? Q.6. Categorize the following as macronutrients and micronutrients: (i) Calcium (ii) Molybdenum (iii) Phosphorus (iv) Iron (v) Boron (vi) Magnesium. Q.7. What is organic farming? Q.8. What is vermicomposting? Q.9. Differentiate between mixed and inter cropping. Q10. What are river lift systems? Q.11. Why are weeds considered as unwanted plants in cultivated lands? Q.12. In what three ways do the pests attack plants? IX CBSE - Formative Assessment-II [SET-2] Q.1. What qualities are expected in a cross-breed variety of fowl? Q.2.

IX Class Question solution for Physics Chapter Sound 1. How sound is produced? Answer:   Sound is produced by the vibration of vibrating object. 2. What do you understand by a ‘wave’? Answer:  A periodic disturbance created in material medium that transfer sound and light energy is called wave. 3. Write three differences between sound and light waves. Answer:   sound wave is Mechanical wave that require material medium for propagation where as light waves are electromagnetic wave that can travel in vacuum. 4. What do you understand by “sound energy cannot be produced”? Answer: Sound energy cannot be produced on its own. Some mechanical energy is required to make an object vibrate. It is the mechanical energy of the vibrating object which travels through a medium and ultimately reaches the ear. 5. What is the name of the wave that can travel through vacuum? Answer:   Electromagnetic wave 6. Explain by some experiment that sound waves require medium for their

HOTS Questions with Answer:   Magnetic Effects of Electric Currents Q1.On what factors does the magnetic field intensity at the centre of the circular coil carrying current  depend ? Answer: The magnetic field intensity at the centre of the circular coil is directly proportional to current and inversely proportional to radius of the coil. So, in both the cases ,that is, twice the current as well as half in radius, the magnetic field intensity gets doubled. The magnitude of the magnetic field (B) at the of the coil is: (i). directly proportional to the current (I) flowing it.       i.e.   B α I                           ① (ii). Inversely proportional to the radius (r) of the coil     i.e.  B α  1/r                               ② From ①, and  ② , we get               B α I/r Q2.State the principle used to determine the force experienced by a conductor carrying current in uniform magnetic field ? Answer: .Fleming’s Left Hand Rule-Stretch the first three fingers