Which information is not conveyed by a balanced chemical equation?

The nature of calcium phosphate is present in tooth enamel is

An alloy is

The correct sequence of anaerobic reactions in yeast is

Which of the following statements are true?
(i) Sudden action in response to something in the environment is called reflex action
(ii) Sensory neurons carry signals from spinal cord to muscles
(iii) Motor neurons carry signals from receptors to spinal cord
(iv) Impulse from a receptor to a muscle or a gland is called reflex arc

A cell, a resistor, a key and ammeter are arranged as shown in the circuit diagrams. The current recorded in the ammeter will be

The phenomenon of electromagnetic induction is 

Choose the incorrect statement

Ethane with the molecular formula C₂H₆ has

Where would you locate the element with electronic configuration 2,8 in the Modern Periodic Table?

Name the gas which burns with pop sound.

What happens to idli dough when it is kept at room temperature on a summer day?

Silver articles develop black coating and copper articles develop green coating. Which chemical phenomenon is responsible for this coating?

The pH value of three solutions A, B, and C having equal molar concentration are respectively 2.0, 7.0, and 13.0 at 298 K.  Which of the three solutions represents an acid solution?

Given below are the pH values of four different liquids : 7.0, 14.0, 4.0, 2.0
Which of these could be that of
(i) lemon juice,
(ii) distilled water,
(iii) 1 M sodium hydroxide solution,
(iv) tomato juice

What are ionic bonds?

Name two allotropes of carbon.

Which gas is liberated when a metal reacts with an acid? How will you test the presence of this gas?

Name an enzyme secreted by salivary glands as well as pancreas.

What is the impact of leakage or loss of blood upon the pressure?

Which product are formed during respiration in our muscles when there is less supply of oxygen?

What is reflex action?

Which part of the brain is concerned with memory?

What are photoreceptors?

How is power related to current and voltage?

Give the unit of power.

Which has a higher resistance: a 50 W lamp bulb or a 25 W lamp bulb and how many times?

What is meant by overloading.

What is electric generator?

How is solenoid different from a coil?

What is meant by the 'calorific value' of a fuel? How is it determined? Arrange the following fuels in a decreasing order of their calorific values: Kerosene, Coal, LPG.

What is energy?

Which is the ultimate source of energy?

Name the carbon compound which on heating with excess of concentrated sulphuric acid at 443 K gives ethene.

What is the difference between two consecutive members in a homologous series in alkanes in terms of:
(i) Molecular mass,
(ii) Number of atoms of elements.

Name the process by which unsaturated fats are changed to saturated fats.

Chlorine, bromine and iodine form a Dobereiner's triad. The atomic masses of chlorine and iodine are 35.5 and 126.9 respectively. Predict the atomic mass of bromine.

State modern periodic law of classification of elements.

How many vertical columns are there in the modern periodic table and what are they called?

What is a balanced chemical equation? Why should chemical equations be balanced?

You might have seen lemon or tamarind juice being used to clean tarnished surface of copper vessels. Explain why these sour substances are effective in cleaning the vessels?

Why metals can be given different shapes according to our needs?

What are the differences between autotrophic nutrition and heterotrophic nutrition?

What happens at the synapse between two neurons?

Why is tungsten metal selected for making filaments of incandescent lamp bulbs?

Draw magnetic field lines around a bar magnet.

What is the cause of release of unusually large energies in nuclear fusion reactions?

Which of the following hydrocarbons undergo addition reaction?
C₂H₆, C₃H₈, C₃H₆, C₂H₂ and CH₄.

Name the first three elements of group 17 of modern periodic table?

Write the steps for balancing the chemical equation for the formation of ammonia by the combination of nitrogen and hydrogen.

When a copper wire was left in silver nitrate solution for sometime, it was observed that the solution turned bluish green.
(i) Explain the observation.
(ii) Write the balanced chemical equation to represent the change taking place.

What is meant by the water of crystallization? How many molecules of water are present in hydrated copper sulphate? Write its formula. What colour change do you observe when it is heated?

Name the three products of 'chlor-alkali' process.Write one commercially or industrially important material each that can be prepared from each of these products

Why do covalent compounds have low melting point?

Give reasons for the following:
(i) Aluminium is a reactive metal but is still used for packing food articles.
(ii) Calcium starts floating when water is added to it.

What is 'translocation'? Why is it essential for plants?Where in plants are the following synthesized:
(i)Sugar  (ii)Hormones

How 'respiration' different from 'breathing'? Explain the processes of 'aerobic' respiration and 'anaerobic' respiration.

Describe the central nervous system in human being under the following heads:
(i) Regions included
(ii) Three functions of any one region

Write down three main differences between auxin and cytokinin.

A touch bulb is rated 2.5 V and 750 mA. Calculate (i) its power, (ii) its resistance and (iii) the energy consumed if this bulb is lighted for four hours.

Differentiate between ammeter and voltmeter.

(a) What are 'magnetic field lines'? How is the direction of a magnetic field at a point determined?
 (b) List any three properties of magnetic field lines.
 (c) Draw two field lines around a bar magnet along its length on its two sides and mark the field directions on them by arrow marks.

Distinguish between permanent magnet and electromagnet.

(a) What is a 'solar cell'?
(b) Why is biogas considered an ideal fuel for domestic use?
(c) Name a device in which controlled chain reaction is used.

(a) Why is the Solar Cooker box covered with a plane glass plate?
(b) Why is energy of water flowering in a river considered to be an indirect form of solar energy?
(c) How is the fission of nucleus brought about?

Give the characteristic tests for the following gases:
(a) CO₂
(b) SO₂
(c) O₂
(d) H₂

Account for the following:
(i) State the relation between hydrogen ion concentration of an aqueous solution and its pH.
(ii) An aqueous solution has a pH value of 7.0. Is this solution acidic, basic or neutral?
(iii) Which has a higher pH value, 1MHCl or 1MNaOH solution?
(iv) Tooth enamel is one of the hardest substances in our body. How does it undergo damage due to eating chocolates and sweets? What should we do to prevent it?
(v)How do [H⁺] ions exist in water?

An element A burns with golden flame in air. It reacts with another element B, atomic number 17 to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also write down the equations for the reactions involved.

Describe the process of urine formation in kidneys.

(a) What is (i) phototropism and (ii) geotropism? With labeled diagrams describe an activity to show that light and gravity change the direction that plant parts grow in.
(b) Mention the role of each of the following plant hormones:
(i) Auxin
(ii) Abscisic acid

How will you conclude that the same potential difference exist across three resistors connected in a parallel arrangement to a battery?

Explain with the help of a labelled diagram the distribution of magnetic field due to a current through a circular loop. Why is it that if a current carrying coil has 'n' turns the field produced at any point is n times as large as that produced by a single turn?

What is biomass? Explain the principle working of a biogas plant using a labelled schematic diagram.

State the reason why carbon can neither form C⁴⁺ cations for C^4- anions, but forms covalent compounds. Also state reasons to explain why covalent compounds:
(a) are bad conductors of electricity?
(b) have low melting and boiling points

(a) Why do we classify elements?
(b) What were the two criteria used by Mendeleev in creating his Periodic Table?
(c) Why did Mendeleev leave some gaps in his Periodic Table?
(d) In Mendeleev's Periodic Table, why was there no mention of Noble gases like Helium, Neon and Argon?
(e) Would you place the two isotopes of chlorine, Cl-35 and Cl-37 in different slots because of their different atomic masses or in the same slot because their chemical properties are the same? Justify your answer.