पीटी मास्टर प्रीतम चंद बहुत सख्त स्वभाव और अनुशासन में रहने वाले इंसान थे। वह छोटी से छोटी गलती पर भी बच्चों को बुरी तरह मारते थे। बच्चों ने उन्हें कभी भी हंसते या मुस्कुराते हुए नहीं देखा था। बच्चे उनसे बहुत डरते थे कि पता नहीं कब खाल खींचने वाला मुहावरा दिखाई दे। बच्चों को स्काउटिंग की परेड का अभ्यास करवाते समय यदि कोई गलती नहीं होती थी तो वह बच्चों को शाबाश कहते थे। बच्चों को वह शाबाश फौज के तमगों जैसी लगती थी। बच्चों को लगता था कि उन्होंने बहुत महत्वपूर्ण कार्य अच्छे तरीके से पूरा किया है इस कारण पीटी साहब से शाबाश रूपी तमगा मिला है।

An indicator is a chemical substance that undergoes a colour change at the endpoint. The endpoint of an acid-base titration can be determined using acid-base indicators. Acid Base indicators are either weak organic acids or weak organic bases. The colour change of an indicator depends on the pH of the medium. The un-ionized form of an indicator has one colour, but its ionized form has a different colour.

Phenolphthalein is used to find the strength of caustic soda solution with the help of oxalic acid

When it changes to curd its pH will decrease. It is because curd contains lactic acid. Since acids generally have a low pH value, when fresh milk changes to curd its pH will decrease.

x²-5x+k

 Here, a=1, b=-5 and c=k 

Now, α+ β = -b/a= -(-5)/1= 5 

α*β  = c/a= k/7= k

 Now,α - β =1

 Squaring both sides, we get,

 (α - β)²=1² 

⇒ α² + β² - 2αβ = 1

⇒ (α² + β² + 2αβ) - 4αβ = 1

⇒ (α +β)² -4αβ =1

⇒ (5)²-4k=1

⇒ -4k= 7-25

 ⇒ -4k= -24 

⇒ k=6 So the value of k is 6. 

The thermite reaction is an exothermic reaction between the metal and metal oxide. For example the reaction between the aluminium with the metal oxides, where aluminium acts as a reducing agent. The aluminium reduces the metal oxide most probably an iron (lll) oxide to produce ferrous and aluminium oxide. During the reaction, large amount of energy is released.

Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat

Total pens=1001
Total pencils=910
we need to find maximum no.of students among whom 1001 pens and 910 pencils can be distributed in such a way that each students get same no.of pens and pencils.
Then we need to find HCF of 1001 and 910
Prime factorization of,
1001=7×11×13
910=2×5×7×13
HCF=product of commom prime factor of least power
HCF=7×13=91
Here HCF of 1001 and 910 is 91.

Hence among 91 students 1001 pens and 910 pencils can be distributed such that each student get same no.of pens and pencils.

Six bells commence tolling together and toll at intervals of 2, 4, 6, 8, 10, 12 minutes respectively.

Hence, using LCM of the given numbers which is 120 we conclude that bell will toll together after 120 seconds = 2 minutes.

In 30 minutes they will toll together in 30/2 = 15  and 1 (at the starting).

Hence, total number of bells together is 15 + 1 = 16

Using Euclid's division lemma

hence HCF is 2. Now starts from second last ewuation

so m=4
n= -59

LCM × HCF = Product of the Numbers

LCM ×  9 = 306 ×  630

LCM = (306 ×  630)/9

LCM = 306 ×  70

LCM= 21420

Resources can be classified on different bases; into following types:

• On the basis of origin: Biotic and Abiotic
• On the basis of exhaustibility: Renewable and Non-renewable
• On the basis of ownership: Individual, community, national and international
• On the basis of status of development: Potential, Developed, Stock and Reserves

x²-14x +13 
 x²-13x - x  +13 = 0

  x ( x - 13) - 1 ( x - 13) = 0

  ( x - 13) ( x-1) = 0

x - 13 = 0 and x- 1 = 0

x = 13 and x = 1

HRD Minister Ramesh Nishank announced a major CBSE syllabus reduction for the new academic year 2020-21 on July 7 which was soon followed by an official notification by CBSE on the same.

Considering the loss of classroom teaching time due to the Covid-19 pandemic and lockdown, CBSE reduced the syllabus of classes 9 to 12 with the help of suggestions from NCERT.

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There are various sources of water. About 97% of the water on the Earth’s surface is covered with water. The three main sources of water are:

• Rainwater.
• Groundwater – This includes water bodies like Wells and Springs.
• Surface water – This includes different water bodies like Sea, Oceans, Reservoirs, Rivers, Streams, Ponds, Lakes and Tanks.

Glycolysis is the process in which glucose is broken down to produce energy. It produces two molecules of pyruvate, ATP, NADH and water. The process takes place in the cytosol of the cell cytoplasm, in the presence or absence of oxygen.
Glycolysis is the primary step of cellular respiration. In the absence of oxygen, the cells take small amounts of ATP through the process of fermentation.

• Dravidians came to India before the Aryans. They spoke Dravidian language.
• They were the inhabitants of the Mohen-jo-daro culture. The Dravidians worshipped the mother as a ‘goddess’ and Shiva as a ‘God’.
•  The tradition of worshiping with incense stick, lamp and ‘aarti’ are considered as the greatest gifts of the Aryans.
• They had matriarchal system of family and they were perfect in the art of weaving, spinning, dyeing and arts.
• After the Aryans settled in north India, the Dravidians shifted to North India. Toady they speak Dravidian- family languages like Tamil, Telugu, Kannada and Malyalam.

The Aryans

• According to most historians, the Aryans came into India in around 1500 BCE from central Asia. They were war-like people.
• The Aryans worshipped the relief features and the forces of nature like trees, rivers, mountains, Sun, wind and rain. They composed hymns for praying various natural elements.
• The Nordic Aryans were the creator of the Indian culture.

Mixed economic system has been followed by INDIA.

Indian economy is called a mixed economy because it is neither completely socialist nor capitalist . In India private & public sector both operate in the market. 

In a mixed economy, private and public sectors go side by side. The government directs economic activity in some socially important areas of the economy, the rest being left to the price mechanism to operate.

In case of kidney failure, accumulation of poisonous wastes takes place in the kidneys, which can be fatal. In such cases, hemodialysis is employed. It is a method for removing waste products such as potassium and urea, as well as free water from the blood in case of renal failure.

In hemodialysis, the patient's blood is pumped through the blood compartment of a dialyzer, exposing it to a semipermeable membrane. During this passage, the waste products from the blood pass into the dialysing fluid by diffusion. The purified blood is then returned via the circuit back to the body. Here, ultrafiltration occurs by increasing the hydrostatic pressure across the dialyzer membrane. This is done by applying a negative pressure to the dialysate compartment of the dialyzer. This pressure gradient causes water and dissolved solutes to move from blood to dialysate, and allows removal of several litres of excess fluid during a typical 3 to 5 hour treatment. This is similar to the function of kidney, but it is different since there is no reabsorption involved