Name the target organs of the following diseases:
Question: Name the target organs of the following diseases: Hepatitis targets . Fit or unconsciousness targets . Pneumonia targets . . Fungal disease targets . . Solution: 1. Liver 2. Brain 3. Lungs 4. Skin....
Read More →Solve this
Question: If $\left[\begin{array}{cc}2 x+1 5 x \\ 0 y^{2}+1\end{array}\right]=\left[\begin{array}{cc}x+3 10 \\ 0 26\end{array}\right]$, find the value of $(x+y)$ Solution: As the given matrices are equal, therefore, their corresponding elements must be equal. Comparing the corresponding elements, we get $2 x+1=x+3 \quad 5 x=10$ $0=0 \quad y^{2}+1=26$ On simplifying, we get $x=2$ and $y=\pm 5$ Therefore, $x+y=2+5=7$ or $x+y=2-5=-3$ Hence, the value of $(x+y)$ is $7,-3$...
Read More →Fill in the blocks :
Question: Fill in the blocks : Pneumonia is an example of disease. Many skin diseases are caused by .. . Antibiotics commonly block biochemical pathways important for the growth of .. . Living organisms carrying the infecting agents from one person to another are called . . Solution: 1. Communicable (infectious) 2. fungi 3. bacteria 4. vectors....
Read More →What is antibiotic?
Question: What is antibiotic? Give two examples. (CCE 2012) Solution: Antibiotic. It is a biochemical produced by a microbe which kills or blocks growth of other microbes (e.g. bacteria) by blocking their life processes without harming human cells, e.g., Penicillin, Streptomycin....
Read More →Which bacterium causes peptic ulcers?
Question: Which bacterium causes peptic ulcers? Who discovered the pathogen for the first time? Solution: Bacterium Causing Peptic Ulcers. Helicobacter pylori Discovery. Warren (1984). Marshall and Warren (1985)....
Read More →Name two diseases caused by protozoans.
Question: Name two diseases caused by protozoans. What are their causal organisms? Solution: 1. Sleeping Sickness, caused by Trypanosoma gambiense. 2. Kala-azar, caused by Leishmania donovani....
Read More →If the matrix
Question: If the matrix $A=\left[\begin{array}{ccc}0 a -3 \\ 2 0 -1 \\ b 1 0\end{array}\right]$ is skew-symmetric, find the value of ' $a$ ' and ' $b$ '. Solution: $A=\left[\begin{array}{ccc}0 a -3 \\ 2 0 -1 \\ b 1 0\end{array}\right]$ If matrix $\mathrm{A}$ is a skew-symmetric matrix then, $A^{T}=-A$ $\left[\begin{array}{ccc}0 2 b \\ a 0 1 \\ -3 -1 0\end{array}\right]=-\left[\begin{array}{ccc}0 a -3 \\ 2 0 -1 \\ b 1 0\end{array}\right]$ $\Rightarrow\left[\begin{array}{ccc}0 2 b \\ a 0 1 \\ -3 -...
Read More →Give two examples for each of the following :
Question: Give two examples for each of the following : 1. Acute diseases 2. Chronic diseases 3. Infectious diseases 4. Non-infectious diseases. Solution: 1. Acute Diseases. Typhoid, Malaria, Influenza. 2. Chronic Diseases. TB (tuberculosis), Elephantiasis. 3. Infectious Diseases. Typhoid, Chicken Pox. 4. Non-infectious Diseases. Diabetes, Goitre....
Read More →Let A and B be matrices of orders 3×2 and 2×4 respectively. Write the order of matrix AB.
Question: Let $A$ and $B$ be matrices of orders $3 \times 2$ and $2 \times 4$ respectively. Write the order of matrix $A B$. Solution: Since, the order of matrix $A$ is $3 \times 2$ and order of matrix $B$ is $2 \times 4$. So, the order of $A B$ will be the "number of rows of $A \times$ number of columns of $B^{\prime \prime}=3 \times 4$...
Read More →Draw a curve showing density or pressure variations
Question: Draw a curve showing density or pressure variations with respect to distance for a disturbance produced by sound. Mark the position of compression and rarefaction on this curve. Also define wavelengths and time period using this curve. (CBSE 2012) Solution: Wavelength : Distance between two successive compressions or two successive rarefactions. Time Period: Time taken by the disturabnce to travel between two successive compressions or between two successive rarefaction....
Read More →Let A and B be matrices of orders 3×2 and 2×4 respectively. Write the order of matrix AB.
Question: Let $A$ and $B$ be matrices of orders $3 \times 2$ and $2 \times 4$ respectively. Write the order of matrix $A B$. Solution: Since, the order of matrixAis32 and order of matrixBis24.So, the order ofABwill be the "number of rows ofAnumber of columns ofB" = 34...
Read More →Establish the relationship between speed of sound,
Question: Establish the relationship between speed of sound, its wavelength and frequency. If velocity of sound in air is $340 \mathrm{~m} \mathrm{~s}^{-1}$, calculate (i) wavelength when frequency is $256 \mathrm{~Hz}$. (ii) frequency when wavelength is $0.85 \mathrm{~m}$. (CBSE 2012) Solution: Refer Article 6.2.5. (i) $\lambda=\frac{v}{v}=\frac{340}{256}=1.33 \mathrm{~m}$ (ii) $v=\frac{v}{\lambda}=\frac{340}{0.84}=400 \mathrm{~Hz}$....
Read More →Solve the following equations
Question: If $\mathrm{A}=\left(\begin{array}{ll}3 5 \\ 7 9\end{array}\right)$ is written as $A=P+Q$, where as $A=P+Q$, where $P$ is a symmetric matrix and $Q$ is skew symmetric matrix, then write the matrix $P$. Solution: $A=\left[\begin{array}{ll}3 5 \\ 7 9\end{array}\right]$ $P$ is symmetric matrix. So, $P=\frac{1}{2}\left(A+A^{T}\right)$ $Q$ is skew symmetric matrix. So, $Q=\frac{1}{2}\left(A-A^{T}\right)$ $A^{T}=\left[\begin{array}{ll}3 7 \\ 5 9\end{array}\right]$ $P=\frac{1}{2}\left[\begin{...
Read More →Represent graphically by two separate diagrams in each case:
Question: Represent graphically by two separate diagrams in each case: (i) Two sound waves having the same amplitude but different frequencies? (ii) Two sound waves having the same frequency but different amplitudes. (iii) Two sound waves having the different amplitude but different wavelengths. Solution:...
Read More →Solve the following matrix
Question: If $\left[\begin{array}{lll}2 1 3\end{array}\right]\left(\begin{array}{ccc}-1 0 -1 \\ -1 1 0 \\ 0 1 1\end{array}\right)\left(\begin{array}{c}1 \\ 0 \\ -1\end{array}\right)=A$, then write the order of matrix $A$. Solution: Consider, $\left(\begin{array}{lll}2 1 3\end{array}\right)\left(\begin{array}{ccc}-1 0 -1 \\ -1 1 0 \\ 0 1 1\end{array}\right)\left(\begin{array}{c}1 \\ 0 \\ -1\end{array}\right)=\mathrm{A}$ Order of matrix $(213)$ is $1 \times 3$. Order of matrix $\left(\begin{array}...
Read More →Why is the ceiling and wall behind
Question: Why is the ceiling and wall behind the stage of good conference halls or concert halls made curved? Solution: So that sound after reflection reach to every audience....
Read More →find the square roots of the following:
Question: Given that: $\sqrt{2}=1.414, \sqrt{3}=1.732, \sqrt{5}=2.236$ and $\sqrt{7}=2.646$, find the square roots of the following: (i) $\sqrt{\frac{196}{75}}=\frac{14}{5 \sqrt{3}}=\frac{14}{5 \times 1.732}=1.617$ (ii) $\sqrt{\frac{400}{63}}=\frac{20}{3 \sqrt{7}}=\frac{20}{3 \times 2.646}=2.520$ (iii) $\sqrt{\frac{150}{7}}=\frac{5 \sqrt{2} \times \sqrt{3}}{\sqrt{7}}=\frac{5 \times 1.414 \times 1.732}{2.646}=4.628$ (iv) $\sqrt{\frac{256}{5}}=\frac{16}{\sqrt{5}}=\frac{16}{2.236}=7.155$ $(\mathrm{...
Read More →find the square roots of the following:
Question: Given that: $\sqrt{2}=1.414, \sqrt{3}=1.732, \sqrt{5}=2.236$ and $\sqrt{7}=2.646$, find the square roots of the following: (i) $\sqrt{\frac{196}{75}}=\frac{14}{5 \sqrt{3}}=\frac{14}{5 \times 1.732}=1.617$ (ii) $\sqrt{\frac{400}{63}}=\frac{20}{3 \sqrt{7}}=\frac{20}{3 \times 2.646}=2.520$ (iii) $\sqrt{\frac{150}{7}}=\frac{5 \sqrt{2} \times \sqrt{3}}{\sqrt{7}}=\frac{5 \times 1.414 \times 1.732}{2.646}=4.628$ (iv) $\sqrt{\frac{256}{5}}=\frac{16}{\sqrt{5}}=\frac{16}{2.236}=7.155$ $(\mathrm{...
Read More →Write the number of all possible matrices of order 2 × 2 with each entry 1, 2 or 3.
Question: Write the number of all possible matrices of order $2 \times 2$ with each entry 1,2 or 3 . Solution: As matrices is of order 2 2, so there are 4 entries possible.Each entry has 3 choices that are 1, 2 or 3 So, number of ways to make up such matrices are $3 \times 3 \times 3 \times 3$ i.e, $3^{4}$ times or 81 times....
Read More →Sound produced by a thunderstorm is heard
Question: Sound produced by a thunderstorm is heard $10 \mathrm{~s}$ after the lightning is seen. Calculate the approximate distance of the thunder cloud. (Given speed of sound $=340 \mathrm{~m} \mathrm{~s}^{-1}$ ). Solution: Distance of thunder cloud $=$ speed of sound $x$ time $=340 \times 10=3400 \mathrm{~m}=3.4 \mathrm{~km}$....
Read More →If any explosion takes place at the bottom of a lake,
Question: If any explosion takes place at the bottom of a lake, what type of shock waves in water will take place? Solution: Longitudinal wave as transverse wave cannot travel in water....
Read More →Solve the following matrices
Question: Matrix $A=\left[\begin{array}{rcr}0 2 b -2 \\ 3 1 3 \\ 3 a 3 -1\end{array}\right]$ is given to be symmetric, find values of $a$ and $b$. Solution: We have $A=\left[\begin{array}{ccc}0 2 b -2 \\ 3 1 3 \\ 3 a 3 -1\end{array}\right]$ $A^{\prime}=\left[\begin{array}{ccc}0 3 3 a \\ 2 b 1 3 \\ -2 3 -1\end{array}\right]$ We know that a matrix is symmetric if $A=A^{\prime}$. Thus, $\left[\begin{array}{ccc}0 2 b -2 \\ 3 1 3 \\ 3 a 3 -1\end{array}\right]=\left[\begin{array}{ccc}0 3 3 a \\ 2 b 1 ...
Read More →Why do we hear the sound produced
Question: Why do we hear the sound produced by the humming bees while the sound of vibrations of pendulum is not heard? Solution: This is because the frequency of sound produced by humming bees lies in audible range $(20 \mathrm{~Hz}$ to 20,000 $\mathrm{Hz}$ ) and frequency of the sound of vibrations of pendulum lies in infrasonic region. ( $1 \mathrm{~Hz}$ to $19 \mathrm{~Hz}$ )...
Read More →A girl is sitting in the middle of a park of dimension
Question: A girl is sitting in the middle of a park of dimension $12 \mathrm{~m} \times 12 \mathrm{~m}$. On the left side of it, there is a building adjoining the park and on the right side of the park, there is a road adjoining by park. A sound is produced on the road by a cracker. Is it possible for the girl to hear the echo of this sound? Explain your answer. Solution: To hear echo, the distance between the source of sound and the obstacle (i.e., building) should be more than $17 \mathrm{~m}$...
Read More →valuate each of the following:
Question: Given that: $\sqrt{2}=1.414, \sqrt{3}=1.732, \sqrt{5}=2.236$ and $\sqrt{7}=2.646$, evaluate each of the following: (i) $\sqrt{\frac{144}{7}}$ (ii) $\sqrt{\frac{2500}{3}}$ Solution: Given: $\sqrt{7}=2.646$ $(i) \sqrt{\frac{144}{7}}=\frac{\sqrt{144}}{\sqrt{7}}=\frac{12}{2.646}=4.536$ Given: $\sqrt{3}=1.732$ (ii) $\sqrt{\frac{2500}{3}}=\frac{\sqrt{2500}}{\sqrt{3}}=\frac{50}{1.732}=28.867$...
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