PORTFOLIO SCIENCE.pptx for science Holiday Homework

This is a Science Portfolio for your School projects or homework.

1. PORTFOLIO SCIENCE

2. INTRODUCTION Name – Jatin Kumar Roll Number – 11 Class - 10 ‘B’ Subject – SCIENCE School – Global Public School

3. ACTIVITIES S. no. Name 1 PHYSICS To study the dependence of potential difference (V) across a resistor on the current ( i ) passing through it and determine its resistance. Also plot a graph between V and I. 2 BIOLOGY To show experimentally that carbon dioxide is given out during respiration. 3 CHEMISTRY To find the pH of the following samples by using pH paper. 1. Dilute hydrochloric acid solution 2. sodium hydroxide solution 3. Dilute ethanoic acid solution Dilute 4. Lemon juice 5. Water 6. Dilute sodium bicarbonate solution

4. PHYSICS Objective :- To study the dependence of potential difference (V) across a resistor on the current (I) passing through it and determine its resistance. Also plot a graph between V and I. Materials Required :- Rheostat, battery or eliminator, plug key, d.c. volt meter, d.c. ammeter, a nichrome or manganin resistance, connecting wires and sand paper. Theory :- According to Ohm's law, physical conditions of the conductor remaining same, the electric current flowing through a conductor is directly proportional to the potential difference across the two ends of the conductor, i.e. = Vα I. So if we plot a graph of different values of V against corresponding values of I, we get a straight line passing through the origin. Procedure :- 1. Rub the bare ends of the connecting wires with sand paper, so that bright shining copper metal is seen. 2. Draw a circuit diagram as shown in Fig. 1.1. 3.Arrange the circuit as shown in diagram. Connect, the key, the rheostat, the ammeter and the resistor in series with the connecting wires to the dry cell and connect a voltmeter in parallel to the resistor.

5. PHYSICS

6. 4.Note down the least count of the ammeter and voltmeter and also their zero errors (if any). 5.Insert the plug key into the key and adjust the rheostat to pass a small current through the given resistor. 6.Note down the readings of the voltmeter and ammeter. 7.Increase gradually the amount of current passing through the given resistor by adjusting the rheostat and record 4 more sets of observations (i.e. readings of the voltmeter and the ammeter). 8. Calculate R = V/I for each set of observations, and find out the mean value of R. 9.Plot the graph between V and I, taking V along X-axis and I along Y-axis. Observations :- Least count of the ammeter =A Zero error of the ammeter=A Least count of the voltmeter =V Zero error of the voltmeter=V Mean value of R = ______________ ohms Observe that the graph between V and I is a straight line passing through the origin.

7. Results :- ( i ) The graph between V and I is a straight line. Hence, V α I i . e. voltage is directly proportional to the current applied. (ii) The resistance of the given resistor is_______ohms . Precautions :- 1.The ends of the connecting wires should be cleaned with sand paper before making the connections. 2.All the connections should be tight. 3.The plug should be inserted into the key only while taking the reading. It should be removed as soon as you have noted the reading. S. no. Ammeter reading I (in A) Voltmeter reading V (in V) Resistance (in Ohms) R= R I Observes Corrected Observes Corrected 1 2 3 4 5

8.  BIOLOGY Objective :- To show experimentally that carbon dioxide is given out during respiration. Materials Required:- A conical flask, beaker, test tube, KOH pellets, a delivery tube bent twice at right angles, cork, thread, germinating seeds, colored water. Theory :- 1. Each and every living cell of the organism respires all the time. 2.Respiration is the process of oxidation or breaking down of food (glucose) in the living cells with the release of energy. Types of respiration:- ( i ) Aerobic respiration:- Free oxygen is used for complete oxidation of substrates forming CO 2 and water and releases energy as ATP (Adenosine triphosphate). (ii) Anaerobic respiration:- It is incomplete oxidation of substrates without using free oxygen so that end products are carbon dioxide and ethyl alcohol, e.g. yeast, skeletal muscles.

9. BIOLOGY

10.  4. The organic compounds which are oxidised during respiration are known as respiratory substrate. 5. All the reactions that are involved in the oxidation of food inside the cell, i.e., glycolysis (breaking down of glucose food into pyruvic acid) and Kreb's cycle (breaking down of pyruvic acid into Co 2 and H 2 O) constitute cellular respiration. Procedure :- 1.Arrange the experimental set up as shown in Fig. 2.1. 2.Place moist germinating seeds in the conical flask. 3. Suspend a test tube containing KOH pallets. 4. Fit a cork in conical flask with a glass tube as shown in the figure. 5.Dip the free end of bent tube in a beaker containing coloured water. Mark the initial level of water 6.Keep the set up undisturbed for 15 minutes and mark the final level of water. Observations :- 1.The level of water in the bent tube rises up. 2.Germinating seeds consume oxygen during respiration and give out carbondioxide .

11.  3.Carbondixoide is absorbed by KOH pallets and a partial vacuum is created in the flask. 4.To fill up this vacuum, air from the bent tube is pulled up and the water level rises in the bent tube. 5. This rise of water level is proportional to the amount of CO, produced by the germinating seeds. Inference :- CO, is produced during respiration. Precautions :- 1.The apparatus should be air-tight. 2. Seeds should be in the process of germination. 3.Seeds should be in sufficient quantity.

12. CHEMISTRY Objective:- To find the pH of the following samples by using pH paper. 1. Dilute hydrochloric acid solution 2. sodium hydroxide solution 3. Dilute ethanoic acid solution Dilute 4. Lemon juice 5. Water 6. Dilute sodium bicarbonate solution Materials Required :- Test tubes, test tube stand, glass rod or a dropper, white glazed tile, pH paper or universal indicator, distilled water, given samples etc. Theory :- The pH of a solution is defined as the negative logarithm to the base 10 of the hydrogen ion concentration (H + ) in moles per litre pH = -log [H + ] Mathematically, pH = -log 10 [H + ] As H + is associated with water molecules, we normally write H + as H 3 O + and thus pH = -log 10 [H 3 O] + ( i ) The pH of the solution indicates the nature of the solution If pH=7, it indicates that it is a neutral solution pH = -log 10 [H + ] 7=-log 10 [H + ] H + =1x 10 -7 mol/L

13. CHEMISTRY

14. Since pure water is neutral, pH of 7 indicates a neutral solution. Therefore, in pure water the concentration of H + ions is equal to the OH - ions. (ii) For acidic solution pH <7, i . e. [H + ]> 1 x 10 -7 M (iii) For basic solution pH >7, i.e. [H + ] <1× 107 -7 The pH scale Procedure:- (A) To find the pH of the given sample by using wide range pH paper :- 1. Place six clean and dry test tubes in a test tube stand and label them as I to VI. Pour 10 mL of each sample whose pH is to be determined into the six test tubes.  2.Tear a small portion (1-2 cm) of pH paper with clear and dry hands and place it on a white glazed tile. 3.Using a glass rod or a dropper transfer 1 to 2 drops of the I test sample on to the universal indicator paper (pH paper). 4.Observe the colour developed on the pH paper and compare it with the colours in the colour chart on the cover of the pH booklet. 5.Note the pH given against the colour which tallies most with the colour developed in the pH paper. 6.Repeat this experiment for other samples and note your observations.

15.    (B) To find the pH of the given sample by using universal indicator solution:- 1. Place six test tubes in a test tube stand, mark them as A, B, C, D, E and F. Pour 10 mL of each sample whose pH value is to be determined into the six test tubes. 2.Using a glass rod or a dropper, add two drops of BDH universal indicator solution to each of these test tubes. 3. Observe the colour of the solution in each case and match it with different shades, given on the universal indicator solution bottle. Note down the pH corresponding to the colour which matches most in each case.    

16. Observation:-   Results:- 1. The pH values of dilute hydrochloric acid, dilute solution of ethanoic acid and lemon juice are less than 7. Therefore, these have acidic character. 2. The pH values of dilute solution of sodium hydroxide and dilute solution of sodium bicarbonate are more than 7. Therefore, these have basic character. 3.The pH value of distilled water is 7. Therefore, it has neutral character. S.no. Sample Colour produced Approximate pH 1 Dilute hydrochloric acid solution 2 Dilute sodium hydroxide solution 3 3. Dilute ethanoic acid solution 4 4. Lemon juice 5 5. Water 6 . Dilute sodium bicarbonate solution

17. Precautions:- 1.Glass rod used for one sample should be used for other sample only after washing with water. 2.Wash the test tubes thoroughly with distilled water, before use. 3.Clean and dry the glazed tile before use.