formative assessment – i home assignment (2015

Maximum Marks: 50
Subject: SCIENCE
Date : ___________
Marks :____
Signature of Examiner:________
Name:____________________ Sec:____
Roll no._____
Q 1 i) A wire is drawn such that its radius changes from r to 2r.Calculate the new resistance?
ii)Three copper wires have lengths and cross sectional areas as (l,A);(2l,A/2) and (l/2,2A).In which wire
the resistance would be minimum?
Q 2 . Draw an electric circuit consisting of 6v battery ,a rheostat, voltmeter, ammeter ,key and two resistor of
resistance 5Ω each connected in parallel along with a resistance of 10Ω connected in series? Also calculate
the equivalent resistance of the combination?
Q 3 .a. Explain why parallel connection is preferred over series in domestic wiring ?
b. alloys are used for heating elements
c. copper and aluminium are preferred for electrical
Q4 . Graphs between electric current and potential difference across two conductors A and B are as shown in
fig 1.
Which of the two conductors has more resistance?
If A and B are replaced by series and parallel then how would you label it and why?
Fig 1
Q5 .A wire whose resistance is 100 ohm is cut into 4 pieces of equal lengths which are then arranged in
parallel. Calculate the resistance of the combination.
Q6. Calculate the equivalent resistance in the diagram given below between the points i) A and D ii) B and
C assuming that there is a resistance of 5 ohm in each arm of the hexagon.
( 3)
1) Write uses and composition of:
a) Constantan, b) Bell metal, c) Gun metal, d) German silver, e) Silver nitrate, f) Silver
bromide, g)Dolomite, h) Pyrolusite, i) Steel, j) Nichrome.
2) From the following Oxidation and Reduction reactions mention the substance which (a)
oxidizes, (b) Reduces, (c) Oxidizing agent, (d) Reducing agent.
(i) MnO2 + HCl → MnCl2 + H2O + Cl2
(ii) H2S + O2 → H2O + SO2
3) You are provided with two containers made up of (a) dil HCl (b) Alluminum.You are also
provided with solutions of (a) dil HCl (b) dil HNO3 (c) ZnCl2 and (d) H2O. In which of the
above containers these solutions can be kept? Justify it.
4) A silver turns black when kept in the open air for a few days. The article when rubbed with
toothpaste again shinning.
a) Why do silver articles turned black when kept in the open air for a few days. Name the
phenomenon involved.
b) Name the black substance formed and give its chemical formula.
5) Give the characteristic tests and chemical reaction involved in the following if possible:
a) CO2, b) SO2, c) O2 and d) H2.
6) What happened when Zn granules are treated with dilute solution of H2SO4, HCl, HNO3 and
NaOH. Also write the chemical equations if reaction occurs.
1. Draw a well labeled diagram of human digestive system and label the following
a. Salivary gland ( Paroteid)
b. Pancreas
c. Gall bladder
d. Duodenum
e. Caecum
f. Rectum.
2. Demonstrate the activity “ chlorophyll is needed for photosynthesis.”
3. Explain with diagram the structure of stomata in morning, at noon and evening.
4. Draw the respiratory system of man and label the following : Nasal passage, Pharynx, epiglottis, trachea.
,bronchus, bronchiole and diaphragm.
5. Explain anaerobic respiration in a. yeast b. muscle cells.
6. State the differences between ; - a. Aerobic respiration and anaerobic respiration . b. Photosynthesis &
7. What is Dental caries ? How is it formed ? Write the dental formula of a child and an adult man .