सूक्ष्मजीव : मित्र एवं शत्रु | Class 8 विज्ञान | 7 PM Class by Amba Ma'am | L2 | Hindi Medium

12 PM Special Class | Class 11 - STRUCTURE OF ATOM || BOHR MODEL By Yakshu Ma'am

Ratio of the fares of First ,Second and Third class catogory of a train , between two stations is 10:7:2 and the ratio of passenger travelling in these category is 4:9:17 respectively .If the fare is increased by 1/4 in First class , 1/8 in second class and decreased by 10% i Third Class and the ratio of number of passenger in the category remains same .If the total amount received of Rs. 60590 , then find the total amount received from thrid class category .

Thirty children were asked about the number of hours they watched TV programmes in the previous week. The results were found as follows: 1 6 2 3 5 12 5 8 4 8 10 3 4 12 2 8 15 1 17 6 3 2 8 5 9 6 8 7 14 12 (i) Make a grouped frequency distribution table for this data, taking class width 5 and one of the class intervals as 5 - 10. (ii) How many children watched television for 15 or more hours a week?

The average weight of a certain number of students in a class is 68.5 kg. If 4 new students having weights 72.2 kg, 70.8kg, 70.3kg and 66.7 kg join the class, then the average weight of all the students increases by 300 g. The number of students in the class, initially is: किसी कक्षा में छात्रों की एक निश्चित संख्या का औसत वज़न 68.5 किलो ग्राम है | यदि 4 नए छात्र कक्षा में आ जाते हैं, जिनका वज़न क्रमशः 72.2 किलो ग्राम, 70.8 किलो ग्राम, 70.3 किलो ग्राम तथा 66.7 किलो ग्राम है, तो सभी छात्रों का औसत वज़न 300 ग्राम से बढ़ जाता है | आरंभ में कक्षामें छात्रों की संख्या कितनी थी ?

KMnO_4 is prepared from the mineral pyrolusite, MnO_2 (deep purple colour). It acts as an oxidising agent in the neutral, alkaline as well as acidic medium in acidic medium it is used in volumetric analysis for estimation of Fe^(2+) , Cr_2O_4^(2-) salts etc. The titrations are carried out in presence of H_2SO_4 . However, before using it as a titrant, it is first standardised with standard oxalic acid solution or Mohr's salt solution . In one of the experiments on titration 26.8g of dry pure sodium oxalate (Mw=123gmol^-1) was dissolved in 1L of distilled water and then 100 mL of 2MH_2SO_4 were added. The solution was cooled. Now to this solution 0.1MKMnO_4 solution was added till a very faint pink colour persisted. Q. Mohr's salt, FeSO_4(NH_4)_2SO_46H_2O , is preffered over FeSO_4.7H_2O for standardisation of KMnO_4 solution because.

KMnO_4 is prepared from the mineral pyrolusite, MnO_2 (deep purple colour). It acts as an oxidising agent in the neutral, alkaline as well as acidic medium in acidic medium it is used in volumetric analysis for estimation of Fe^(2+) , Cr_2O_4^(2-) salts etc. The titrations are carried out in presence of H_2SO_4 . However, before using it as a titrant, it is first standardised with standard oxalic acid solution or Mohr's salt solution . In one of the experiments on titration 26.8g of dry pure sodium oxalate (Mw=123gmol^-1) was dissolved in 1L of distilled water and then 100 mL of 2MH_2SO_4 were added. The solution was cooled. Now to this solution 0.1MKMnO_4 solution was added till a very faint pink colour persisted. Q. If 0.1MK_2Cr_2O_7 solution were used in place of 0.1 MKMnO_4 solution used would be

The marks obtained by 40 students of class IX in an examination are given below: 18, 8, 12, 6, 8, 16, 12, 5, 23, 2, 16, 23, 2, 10, 20, 12, 9, 7, 6, 5, 3, 5, 13, 21, 13, 15, 20, 24, 1, 7, 21, 16, 13, 18, 23, 7, 3, 18, 17, 16 Present the data in the form of a frequency distribution using the same class size, one such class being 15-20 (where 20 is not included)

The marks obtained by 40 students of class VIII in an examination are given below: 18,8,12,0,8,16,12,5,23,2,16,23,2,10,20,12,9,7,6,5,3,5, 13,21,13,15,20,24,1,7,21,16,13,18,23,7,3,18,17,16 Present the data in the form of a frequency distribution using the same class size, one such class being 15-20 (where 20 is not included).