When an acid reacts with metal, a salt and hydrogen are produced: acid + metal → salt + hydrogen An example: nitric acid + calcium → calcium nitrate + hydrogen The salt that is produced depends upon which acid and which metal react. When base reacts with metal, it produces respective salt and hydrogen gas. The presence of hydrogen gas is confirmed by a pop sound that is produced by hydrogen gas when it comes in contact with fire. Sodium hydroxide gives hydrogen gas and sodium zincate when reacts with zinc metal.

Redshirts (Italian Camicie Rosse) or Red coats (Italian Giubbe Rosse) is the name given to the volunteers who followed the Italian patriot Giuseppe Garibaldi during campaigns in Uruguay and Italy, and later his son Ricciotti in Greece and the Balkans, from the 1840s to the 1910s.

Battle of Leipzig, also called Battle of the Nations, (Oct. 16–19, 1813), decisive defeat for Napoleon, resulting in the destruction of what was left of French power in Germany and Poland. Not surprisingly, the day one of the battle ended as a French victory. 16 October: Blücher robbed Napoleon of an expected victory on a stormy autumn day… In the battle to the south of Leipzig, Napoleon on the knoll at Liebertwolkwitz directed a ferocious cannonade at the Russia forces facing them.

decisive defeat for Napoleon, resulting in the destruction of what was left of French power in Germany and Poland. The battle was fought at Leipzig, in Saxony, between approximately 185,000 French and other troops under Napoleon, and approximately 320,000 allied troops, including Austrian, Prussian, Russian, and Swedish forces, commanded respectively by Prince Karl Philipp Schwarzenberg, General Gebhard Leberecht Blücher, General Leonty Leontyevich Bennigsen, and the Swedish crown prince Jean Bernadotte. After his retreat from Russia in 1812, Napoleon mounted a new offensive in Germany in 1813. His armies failed to take Berlin, however, and were forced to withdraw west of the Elbe River. When the allied armies threatened Napoleon’s line of communications through Leipzig, he was forced to concentrate his forces in that city. On October 16 he successfully thwarted the attacks of Schwarzenberg’s 78,000 men from the south and Blücher’s 54,000 men from the north, but he failed to defeat either decisively. The number of troops surrounding him increased during the lull on the 17th, when Bennigsen and Bernadotte arrived.

The Papal States, officially the State of the Church, were a series of territories in the Italian Peninsula under the direct sovereign rule of the pope, from the 8th century until 1870. They were among the major states of Italy from roughly the 8th century until the Kingdom of Piedmont-Sardinia successfully unified the Italian Peninsula by conquest in a campaign virtually concluded in 1861 and definitively in 1870. At their zenith, the Papal States covered most of the modern Italian regions of Lazio (which includes Rome), Marche, Umbria and Romagna, and portions of Emilia. These holdings were considered to be a manifestation of the temporal power of the pope, as opposed to his ecclesiastical primacy.

The Papal States, officially the State of the Church also Dicio Pontificia), were a series of territories in the Italian Peninsula under the direct sovereign rule of the pope, from the 8th century until 1870.

Data Definition Language (DDL) helps you to define the database structure or schema while Data Manipulation language (DML command) allows you to manage the data stored in the database. DDL command is used to create the database schema while DML command is used to populate and manipulate database.  DML is abbreviation of Data Manipulation Language. It is used to retrieve, store, modify, delete, insert and update data in database. Examples: SELECT, UPDATE, INSERT statements DDL DDL is abbreviation of Data Definition Language. It is used to create and modify the structure of database objects in database.

Data Definition Language (DDL) and Data Manipulation Language (DML) together forms a Database Language. The basic difference between DDL and DML is that DDL (Data Definition Language) is used to Specify the database schema database structure.

On the other hand, DML (Data Manipulation Language) is used to access, modify or retrieve the data from the database. 

Atmospheric  refraction  is  the  phenomenon  of  bending  of  light  on  passing  through  the Earth’s atmosphere.  The reason for  this  occurrence is that  the  upper  layers  of  the Earth’s atmosphere are rarer compared to the lower layers.

                    On account of atmospheric refraction of light,

1. The stars seem higher than they actually are.
2. The Sun appears to rise 2 minutes before and set 2 minutes later, increasing the apparent length of the day by 4 minutes.
3. The Sun appears oval at sunrise and sunset, but appears circular at noon.
4. The stars twinkle and planets do not.

Tea and coffee both are important beverage crops. The following are the conditions required for their cultivation:
- Both require similar climate and soil condition.
- Require hot and humid climate, 15^oC to 30^oC temperature, shade of the tree not required for tea.
- Coffee requires 150 to 200 cm rainfall, shade of tree required.
-  200 to 250 cm rainfall for tea is required. 
- Both require well-drained fertile soil rich in organic matter.

Let √2 be a rational number 

Therefore, √2= p/q  [ p and q are in their least terms i.e., HCF of (p,q)=1 and q ≠ 0

On squaring both sides, we get 
                   p²= 2q²                                                                                    ...(1)
Clearly, 2 is a factor of 2q²
⇒ 2 is a factor of p²                                                                    [since, 2q²=p²]
⇒ 2 is a factor of p

 Let p =2 m for all m ( where  m is a positive integer)

Squaring both sides, we get 
            p²= 4 m²                                                                                          ...(2)
From (1) and (2), we get 
           2q² = 4m²      ⇒      q²= 2m²
Clearly, 2 is a factor of 2m²
⇒       2 is a factor of q²                                                      [since, q² = 2m²]
⇒       2 is a factor of q 

Thus, we see that both p and q have common factor 2 which is a contradiction that H.C.F. of (p,q)= 1

     Therefore, Our supposition is wrong

Hence √2 is not a rational number i.e., irrational number.

Count Camillo Cavour played a central position in unifying Italy as one.

Explanation:

• Cavour was a Chief Minister of Sardinia-Piedmont.
• He, along with other leaders like Garibaldi and Victor Emmanuel II, performed a vital role in unifying city-states as a nation called Italy.
• He was aristocratic by birth and had strong liberal sympathy.
• His tactful diplomatic alliance with France led Sardinia- Piedmont to beat the Austrian forces in 1859.

• Double circulation is a process during which blood passes twice through the heart during one complete cycle. This type of circulation is found in amphibians, reptiles, birds, and mammals. However, it is more prominent in birds and mammals as in them the heart is completely divided into four chambers – the right atrium, the right ventricle, the left atrium, and the left ventricle.

The movement of blood in an organism is divided into two parts:

(i) Systemic circulation

(ii) Pulmonary circulation

• Systemic circulation involves the movement of oxygenated blood from the left ventricle of the heart to the aorta. It is then carried by blood through a network of arteries, arterioles, and capillaries to the tissues. From the tissues, the deoxygenated blood is collected by the venules, veins, and vena cava, and is emptied into the left auricle.
• Pulmonary circulation involves the movement of deoxygenated blood from the right ventricle to the pulmonary artery, which then carries blood to the lungs for oxygenation. From the lungs, the oxygenated blood is carried by the pulmonary veins into the left atrium.

Hence, in double circulation, blood has to pass alternately through the lungs and the tissues.

• Significance of double circulation:

The separation of oxygenated and deoxygenated blood allows a more efficient supply of oxygen to the body cells. Blood is circulated to the body tissues through systemic circulation and to the lungs through the pulmonary circulation.

When lead(II) nitrate is heated, it breaks down into yellow colour lead (II) oxide, colourless gas of oxygen and brown colour nitrogen dioxide. The chemical equation for the above reaction is,

2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂

The Congress of Vienna 1814-1815 was hosted by the Austrian statesman and diplomat Klemens Von Metternich.

The primary sector includes all those activities the end purpose of which consists in exploiting natural resources: agriculture, fishing, forestry, mining, deposits. As long as humans are alive on the earth, agriculture is an important occupation throughout the world. Agriculture provides basic raw food which will be processed by food processing industries and converts it into packaged food and flood into markets. Everything you eat includes the produce of agriculture. The primary sector is concerned with the extraction of raw materials. It includes fishing, farming, and mining. Understanding the structure of the economy is critical for both the economic planners and the government of that country to plan, to govern and consistently take the economy towards a growth path.

Laboratory Preparation of Hydrogen:

Hydrogen is prepared in the laboratory by the action of the dilute hydrochloric acid or dilute sulphuric acid on granulated zinc.

Use of Granulated Zinc

Granulated zinc contains an impurity like copper which acts as a positive catalyst. A positive catalyst increases the rate of a chemical equation. This is the reason why granulated zinc is preferred over pure zinc for the laboratory preparation of hydrogen gas.

Reaction:

Collection of Gas: Hydrogen gas is collected by downward displacement of water.