Here is a question about this article: Energy gives rise to weight when it is trapped in a system with zero momentum, where it can be weighed. It is also equivalent to mass, and this mass is always associated with it. Mass is also equivalent to a certain amount of energy, and likewise always appears associated with it, as described in mass-energy equivalence. The formula E = mc, derived by Albert Einstein (1905) quantifies the relationship between rest-mass and rest-energy within the concept of special relativity. In different theoretical frameworks, similar formulas were derived by J. J. Thomson (1881), Henri Poincare (1900), Friedrich Hasenohrl (1904) and others (see Mass-energy equivalence#History for further information).
What is the answer to this question: What quantifies the relationship between rest-mass and rest-energy within the concept of special relativity?
****
So... E = mc

Here is a question about this article: Czech, the official language of the Czech Republic (a member of the European Union since 2004), is one of the EU's official languages and the 2012 Eurobarometer survey found that Czech was the foreign language most often used in Slovakia. Economist Jonathan van Parys collected data on language knowledge in Europe for the 2012 European Day of Languages. The five countries with the greatest use of Czech were the Czech Republic (98.77 percent), Slovakia (24.86 percent), Portugal (1.93 percent), Poland (0.98 percent) and Germany (0.47 percent).
What is the answer to this question: What distinction does Czech have in Slovakia?
****
So... foreign language most often used

Here is a question about this article: India's cotton-processing sector gradually declined during British expansion in India and the establishment of colonial rule during the late 18th and early 19th centuries. This was largely due to aggressive colonialist mercantile policies of the British East India Company, which made cotton processing and manufacturing workshops in India uncompetitive. Indian markets were increasingly forced to supply only raw cotton and, by British-imposed law, to purchase manufactured textiles from Britain.[citation needed]
What is the answer to this question: What cotton products did British law mandate that India was allowed to sell?
****
So...
raw cotton