Insert JavaScripts into head of only one page
Drupal provides theme suggestion for html.tpl.php

you can put html.tpl.php in templates folder inside you theme directory

html--node--id.tpl.php

id will be your page id
e.g. ID = 123, then file name will be html--node--123.tpl.php

Hope this will help.

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For particular block you can use hook_block_view_MODULE_DELTA_alter

@see https://api.drupal.org/api/drupal/modules!block!block.api.php/function/hook_block_view_MODULE_DELTA_alter/7.x

like,

function module_name_hook_view_MODULE_DELTA_alter(&amp;$data, $block) {
  drupal_add_js();
}