Oxiacids part 01 Memorizing Trick for name and formula Vikram Hap chemistry

The students of class IX have made placards showing the symbols of some elements and valencies of these elements. These placards somehow got mixed up as shown below : On this basis of these placards the chemistry teacher, Mrs. Shanti, asked a student Vikas to answer the following questions : (a) Choose the symbol of an element from among the placards which exhibits valencies of 3 and 5. What is the name of is the name of this element ? Is it a metal or a non-metal ? (b) Choose the symbol of an element from the given placards which shows a valency of 2. What is the name of this element ? Is it a metal or a non-metal ? (c) Work out the formula of the compound formed between the element of valency 3 and element of valency 2. Also name this compound (d) What values are displayed by Vikas in this episode ?

The Young's modulus Y is determined by stretching a wire by using the formula , Y = (4FL)/(pi d^(2)l) where F is the streching force , L is length of wire , l is extension in length and d is its diameter . If F is of the order of 500 N and known to 1 part in 1000 L , is of the order of 3 m and measured with an accuracy of 1 mm , l is of the order of 5 mm measured to 0.1 mm and d is of the order of 1 mm measured correct upto 0.01 mm , estimate the percentage error in the measurement of Y .