Reaction of Metals with AcidsU0001f9ea | Science experiments | YOUR CLASS | Arisha Ma'am #shorts #ytshorts

A VI class student was given an experiment, to collect hydrogen gas from the reaction of calcium metal and cold water. He conducted the experiment and collected the hydrogen gas in boiling tube. Which process is involved in collection of hydrogen gas?

Mitaali, a class 10 student wanted to study the speed of reactions of different acids with zinc metal. For this, she conducted the following experiments using zinc metal in excess. She measured the volume of H_2 gas produced at regular time intervals and summarised her results in a graphical form. Which of the following graphs best represents the results obtained in experiments I, II and III?

Figure shows the stopping potential versus the light frequency for a metal cathode used in a photoelectric-effect experiment. Suppose this cathode is now illuminated with 6.63 mu W of 300 nm light and that the efficiency of converting photons to photoelectrons is 10% Take h=6.63xx10^(-34) Jsec, c=3xx10^(8)ms^(-1) What is the power (in watt) of emitted photoelectron beam assuming that on an average, each photoelectron emitted has energy (5K_(max))/6 Assume that anode potential is sufficiently positive. Express your answer in from of 'X' xx 10^(-9) W fill 'X' in OMR sheet after rounding off to nearest integer.

Piyush is a student of class 10. His teacher was teaching the type of chemical reactions in the class. Piyush was aksed to carry out the reaction of electrolysis of water in the laboratory. Piyush set up the complete apparatus for the electrolysis of water. He took pure water (distilled water) to carry out this reaction. When Piyush passed electric current through this water for a considerable time even then no chemical reaction took place. Piyush told this problem to his classmate Arjun. Arjun thought over the problem and asked Piyush to add a little of a certain substance into pure water before passing electric current through it. When electric current was passed thorugh water after adding a little of this substance then a chemical reaction took place to form two gases X and Y . The volume of gas X collected over one of the electrodes was 8mL whreas the volume of gas Y collected over the other electrode was 16mL (a) Why no chemical reaction took place when electric current was passed thorugh pure water? (b) What substance was added in little quantity to pure water before passing electric current again? (c) How did the addition of little of this substance help in the electrolysis of water? (d) What is gas X ? Over which electrode is it collected? (e) What is gas Y ? Over which electrode is it collected? (f) What type of chemical reaction is demonstrated by this experiment ? Why? (g) What values are displayed by Arjun in this episode?

An organization wants to recruit Trainee Officers. Following are the criteria. The candidate must (i) be not less than 21 years of age and not more than 28 years of age as on 1.2.2009. (ii) be a graduate in any discipline with at least 55% marks. (iii) have secured at least 50% marks in selection test. (iv) have secured at least 45% marks in interview. (v) be willing to work anywhere in India. However, if the candidate satisfies all the above-mentioned criteria EXCEPT - (A) at (ii) above but is a postgraduate, the case is to be referred to the Executive Director. (B) at (i) above but has a working experience of at least one year the case is to be referred to the Vice-President. In each of the questions below, information of one candidate is given. You have to take one of the following five dedsions based on the information provided and the criteria and conditions given above. You are not to assume anything other than the information provided in each question. All these cases are given to you as on 1.2.2009. You have to indicate your dedsion by marking answers to each question as follows : Avinash is a Science graduate passed in first class with 63% marks. He has secured 53% and 51 % marks in selection test and interview respectively. He is willing to work anywhere in India. He has been working in the Marketing department of a private organization since July 2007. He was born on 11.6.1980.